Nearly 40 percent of the scientists conducting hands-on research at the National Institutes of Health say they are looking for other jobs or are considering doing so to escape new ethics rules that have curtailed their opportunity to earn outside income.

Most scientists say the ethics crackdown is too severe, and nearly three-quarters of them believe it will hinder the government's ability to attract and keep medical researchers, according to a survey commissioned by the government's premier medical research agency.

The tightened rules were put in place last year after NIH found dozens of scientists had run afoul of existing restrictions on private consulting deals that had enriched them with money from drug and biotechnology companies.

Outside income from such companies is now banned. NIH also is placing greater restrictions and disclosure requirements on employees' financial holdings.

"Of course we are concerned when any employees are saying they might consider leaving as a result of a change of policy," said Dr. Raynard Kington, the agency's principal deputy director. But he said in a telephone interview Friday that the survey results are muddy because they combine both those actively seeking to leave and those thinking about it.

NIH Director Elias Zerhouni, in a letter Thursday to the staff, said the survey "does suggest concerns about the impact of the regulations on recruitment and retention." But he added, "At this time we do not anticipate revisions in the regulations."

About 8,000 NIH employees, or about half the work force, responded to the Internet-based survey.

Employee job satisfaction was high overall, the survey found. But 39 percent of the scientists researching disease and cures — known as tenure and tenure-track scientists — said they actively were seeking new work or considering leaving NIH because of the rules.

Overall, 3,336 NIH scientists responded to the survey, including 512 tenure and tenure-track researchers.

Among all NIH scientists, only 18 percent said they were trying to leave or considering it. Those who are not in the tenure group typically do not conduct research themselves and instead manage outside research conducted with NIH money by universities and other nonfederal entities. They are less likely to have private consulting opportunities.

One-third of all NIH scientists said they believed the new rules will hurt NIH's ability to fulfill its mission, and most said the old rules could have been enforced better rather than tightened.

NIH officials said they now want to question former and potential employees to see how the changes influenced their decisions.