WASHINGTON (AP) _ Diane Atwood and Christie Sens were among the first Americans to exchange paychecks for peace of mind under a law that's two years old today.

The women took advantage of the Family and Medical Leave Act _ the first bill President Clinton signed into law _ which requires employers to offer up to 12 weeks of unpaid leave for medical or family reasons such as serious illness or a birth. The law covers 40 percent of the work force, or some 60 million employees, and businesses with at least 50 workers.

Atwood, of North Little Rock, Ark., told a commission studying the effects of the law on Friday that she used the federally mandated leave to keep her employee medical benefits while battling Hodgkin's disease in 1993 and 1994 _ and to retain her job after the disease went into remission.

``All of my energies needed to be focused on this war (against cancer,) and nothing else,'' Atwood said. ``The act allowed me to do that.''

Sens, of Arlington, Va., said her first-grade teaching job allowed her either six weeks or one year of maternity leave, but she couldn't afford 12 months with no pay and she wanted more than 1 1/2 months to ``bond'' with her child, now 2 years old. So she took 12 weeks of unpaid leave instead.

``My entire family has benefited from this act,'' she said.

Not everybody agreed the act has been a success. Bell Atlantic Corp., for example, said it was losing millions of dollars as workers take 65 percent more sick leave than they did before the law went into effect.

Andy Mekelburg, director of federal relations for Bell Atlantic, said the company has seen a drastic increase in employees skipping work, using the protection of the act to take extended _ and paid _ sick leave offered by the company.

``We embrace the goals of the act, but the definition is so broad that it covers a lot of conditions,'' said Mekelburg, who contends the law makes it difficult to challenge workers' sick leave claims.

The company estimated the law costs $3.5 million to administer and $475 per employee for sick leave per year, a total of $36.7 million.

Labor Secretary Robert Reich and several company executives also testified, saying the law has benefited businesses and workers.

Reich told the panel that despite fears among corporate America, the act didn't result in legal battles or many quibbles. His office has handled only 3,200 complaints _ 90 percent were resolved with a telephone call _ and only one is still pending, he said.