When the Scottish economic development agency injected about $9 million into the biotechnology company Cyclacel last October, the country's enterprise minister explained that ''there could not be a more important company for Scotland's future.''

But only two months later, this flag-bearer for Scottish biotechnology said it would move its headquarters to Short Hills, N.J., and merge with a publicly traded American company.

Cyclacel executives say there was no slight intended to Scotland. ''The issue was one of access to the capital markets of the United States,'' Spiro Rombotis, Cyclacel's chief executive, said in a recent interview. Only American investors, he said, could supply the tens of millions of dollars needed to carry the company's cancer drugs through clinical trials.

Cyclacel is not alone among European biotechnology companies that consider their science second to none, while conceding the superiority of American financial markets. From European countries including Denmark, France and Germany -- and from Australia and New Zealand, too -- a number of biotechnology companies have come to America, in name at least, for greater access to the world's largest investment pool for life sciences. Some also say the United States is a more lucrative market for the drugs they are developing.

The migration trend suggests that money, not molecules, could become the United States' main competitive advantage in biotechnology, a field that is potentially one of the 21st century's premier global industries.

Most of the migrating companies are setting up only small corporate and business offices in the United States, while leaving their scientists back in their home countries. Cyclacel's 65 researchers, for example, remain in Dundee, Scotland, and Cambridge, England, where they have strong ties to local academic communities. Salaries for scientists are not lower in Britain, Mr. Rombotis said, but the company's research is subsidized by the Scottish government.

The United States has long been the biotechnology world's leader and remains so. But when it comes to spinning science into start-ups, other countries have caught up. Europe now has 1,613 biotech companies, more than the 1,415 in the United States, according to Ernst & Young. A decade ago, Europe had only 584 such companies, compared with 1,308 in the United States.

The European companies, though, are typically smaller than their American counterparts -- 45 employees on average, compared with 96 here, according to Critical I, a British consulting firm. More crucially, they often lack the capital to get beyond the early stages of research and development. Last year, biotechnology companies raised only $3.3 billion in Europe, compared with $16 billion in the United States, according to BioCentury, an industry newsletter.

American companies on average also spend 3 times as much on R.& D. and have access to 10 times as much debt financing as their European counterparts, according to a Critical I report released in May by EuropaBio, a trade group based in Brussels. Compared with Europe, it is also much easier for public companies in the United States to raise additional money, through secondary stock offerings or private placements.

Thus the wave of immigrant companies, like the BioVex Group, which was founded near Oxford, England, but moved its headquarters to Cambridge, Mass., last year because it had begun clinical trials of its cancer treatment in the United States and also wanted better access to capital. Although its scientists remain in Britain, BioVex recently used its American base to file for an initial public stock offering on Nasdaq.

Some of the foreign companies intent on a Nasdaq listing have sidestepped an I.P.O. by doing a reverse merger with an American company that has already gone public -- in some cases a biotechnology company that has foundered.

That is what Cyclacel did. It agreed last December to be nominally acquired by Xcyte Therapies of Seattle, although Cyclacel is now the name of the company and the entity in charge. Cyclacel then took advantage of its adopted Nasdaq listing by raising an additional $45 million in April through a private placement of stock and warrants.

Similarly IDM, a French drug developer, completed a reverse merger last August to acquire the Nasdaq listing of Epimmune. IDM is now based in Irvine, Calif., although its research operation and most of its employees remain in France.

Likewise the German company Micromet now has a Nasdaq listing and a base of operations in Carlsbad, Calif., after reverse-merging in May with CancerVax. Most of its operations are still back in the home country.

In May, a company started by venture capitalists in Denmark to develop a drug for osteoporosis went public through a reverse merger with an American shell company, Castle & Morgan Holdings. It then raised $10 million in a private placement, mainly from American investors. Originally called Nordic Bone, the drug company is now based in San Francisco and has a more cosmopolitan name, Osteologix.

There may be limits, though, to the immigration trend.

Industry executives say it has become more difficult than in the past for very young companies to go public on the Nasdaq. A company now usually needs to have drugs at least close to reaching the market before it can be listed. And some small companies say it can be too costly to comply with the financial controls that the Sarbanes-Oxley Act, passed in 2002, has imposed on public companies.

Last year for the first time, the number of biotechnology companies going public in Europe -- 23 -- surpassed the number in the United States, 13, according to Ernst & Young. This year, two American companies have even gone public on the Alternative Investment Market in London instead of in the United States, although neither has moved its headquarters to London.

One of them, Entelos, a Foster City, Calif., developer of computer simulations of diseases, raised about $20 million in the London market. The other Aqua Bounty, a Waltham, Mass., company trying to win approval in the United States for a genetically engineered salmon, raised about $35 million in London.

''I have trouble raising money in the States, and yet you can raise money on a transgenic fish in a place where they'd never allow it,'' said Elliot Entis, the chief executive of Aqua Bounty, referring to opposition to genetically modified foods in Europe.

Asterand, a supplier of tissue samples for pharmaceutical research, did a reverse merger with a publicly traded British company in December to gain a listing in London, even though most of Asterand's operations remain in Detroit.

''The cost of being a U.K. public company is significantly lower'' than in the United States, said Randal Charlton, the chief executive.

Another limiting factor to the immigration trend is that big American investors are increasingly placing some of their financial bets abroad.

''Today you do not need to be listed on Nasdaq,'' said Wolfgang Sohngen, chief executive of Paion, a German company traded on the Frankfurt Stock Exchange. ''Sophisticated investors invest globally.''

Paion, which is developing a stroke drug derived from vampire bat saliva, recently raised 9.44 million Euros in a private stock offering. Among the investors were J. P. Morgan Proprietary Equities of New York and Xmark Opportunity Fund of Stamford, Conn.

There are also logistical challenges in coming to America. Oxxon Therapeutics, a British company, moved its headquarters to Boston two years ago but has since moved back. ''It's extremely difficult to manage small operations on both sides of the Atlantic,'' said Craig R. Smith, Oxxon's chairman.

Yet, for many overseas biotech companies, an American address still seems the best bet for raising money. That is especially so for companies from Australia and New Zealand, which suffer not only from small capital markets in their home countries but isolation from the pharmaceutical mainstream.

When Dianna L. DeVore was chief operating officer of the Australian Stem Cell Center, a government-backed organization, she trumpeted Australia as a leader in the development of regenerative medicine. But now that Ms. DeVore is starting a company, Jiva Biosciences, to commercialize technology developed by research institutes in Melbourne, she is exploring locations in California for her headquarters.

Jiva will do its research in Australia, working on drugs to stimulate tissue repair. But Ms. DeVore, an American, says a California headquarters will give the company access to people experienced in bringing drugs to market, a bigger pool of investors and potential access to the state's planned $3 billion in public spending on stem cell research.

Protemix, a privately held New Zealand company, is setting up its headquarters in San Diego with an eye toward eventually going public. But research will stay in New Zealand, said Larry K. Ellingson, the chief executive. With the New Zealand government subsidizing the research ''we just can't afford to move it,'' he said.

When foreign companies do establish an American beachhead, reaction back home can vary. Some biotechnology boosters in Europe have used the moves to argue that additional tax incentives or other support is needed for European companies.

Some companies, like the British transplant Domantis, argue that having financial and commercial operations in the United States actually benefits the home country by funneling money back to the local economy.

''I think there are a lot of people in the U.K. who think this is an ideal way to exploit the innovation from the U.K.,'' said Bob Connelly, the chief executive of Domantis, which is based in Waltham, Mass. Although started by scientists in Cambridge, England, in 2000, the company planned from the outset to base its chief executive and a few other officers in the United States.

In Scotland, meanwhile, Cyclacel's expatriation did raise eyebrows. But Scottish Enterprise, the government-backed economic development agency that gave Cyclacel the $9 million, put the best face on the situation. It noted that the company's research was staying in Scotland, as it must do until 2010 under the terms of the agreement for the cash infusion.

''We are delighted to see a Scottish company like Cyclacel internationalize in this way,'' Kate Friel, a spokeswoman for Scottish Enterprise, said in a statement sent by e-mail. ''We believe that this move has also enhanced Scotland's global reputation for scientific discovery and exploitation.''