The Food and Drug Administration has reinstated dozens of specialized employees involved in food safety, review of medical devices and other areas who were laid off last week, according to more than a dozen workers who got called back.

The total number of employees recalled was not immediately clear. But a person familiar with the conversations said nearly all of the roughly 180 medical division employees who had been let go would get their jobs back. More than a dozen workers across a handful of teams said that they had received a call or email reinstating their employment; some reported that up to a dozen others on their teams had also been brought back.

The F.D.A. and its parent agency, the Department of Health and Human Services, did not respond to requests for comment.

The workers had been fired as part of the Trump administration’s efforts, led by Elon Musk, to significantly downsize the federal government and cut costs. But the salaries of many of the fired F.D.A. staff members had been funded by fees companies pay the F.D.A., not taxpayer money.

Many of the reinstated jobs were financed by those kinds of fees, but some such employees were still out of work. Those whose job were funded by an excise tax on cigarettes, for example, said they were not called back to work over the weekend. Those workers reviewed applications for new tobacco products and studied the safety of emerging tobacco products, including e-cigarettes and devices that heat up tobacco but do not burn it.

On Friday, The New York Times featured the accounts of laid-off staff members who reviewed the safety of surgical robots, cardiovascular devices and diabetes-care systems that infuse insulin. All had their jobs back as of Monday morning.

AdvaMed, a trade association for medical device makers, had pushed the administration in a letter and in meetings to ensure that workers who review those products got their jobs back. The industry’s funds have helped the device review division hire experts, including doctors with experience using the devices. The industry funds are approved periodically in agreements passed by Congress that also include strict deadlines to make approval decisions.

Reinstated workers, who spoke on the condition of anonymity because they feared retaliation, said about a dozen staffers from the agency’s chief counsel got their jobs back, including lawyers who supported medication policy. About a dozen who oversee cardiovascular devices and another 12 who authorize artificial intelligence software programs were also restored. Others were called back to their jobs assessing food-chemical safety, a priority of the new health secretary, Robert F. Kennedy Jr.

In interviews, employees who returned on Monday reported a feeling of whiplash and frustration, but also of relief to get back to work.

Dr. Robert Califf, F.D.A. commissioner during the Biden administration, called the staff cuts “anti-efficiency” because many recent hires had been recruited to fill knowledge gaps at the agency, including in artificial intelligence and food-chemical safety. He also said the cuts were made with no regard to well-being of workers.

“It’s despicable to treat fellow human beings this way and a sign of immaturity of the people doing it,” he said in a text message on Monday.

The fired workers had uniformly been told that their performance was “not adequate to justify further employment by the agency.” Yet many of the dismissed workers — reinstated and not — said their performance reviews from the agency had been excellent.

Alice Callahan contributed reporting.