CHICAGO - There's a grim, rarely talked-about twist to all that medical know-how doctors learn to save lives: It makes them especially good at ending their own.

An estimated 300 to 400 U.S. doctors kill themselves each year -- a suicide rate thought to be higher than in the general population, although exact figures are hard to come by.

Some doctors think the stigma of mental illness is magnified in a profession that prides itself on stoicism and bravado. Many fear admitting psychiatric problems could be fatal to their careers, so they suffer in silence.

And when the pain is too much, doctors have easy access to prescription drugs and a precise knowledge of both how the body works and the amount of a drug needed for an overdose to stop breathing and halt the heart.

"All physicians have access to neat, clean ways to commit suicide," said Dr. Robert Lehmberg, a Little Rock, Ark., surgeon who has battled depression and long considered suicide "an exit strategy if absolutely necessary."

The American Medical Association has called physician suicide "an endemic catastrophe," and pledged two years ago to work to prevent the problem.

But the suicides have persisted. So the American Foundation for Suicide Prevention has started an educational campaign in hopes of making troubled doctors more willing to seek help.

The foundation, the American College of Psychiatrists and Wyeth Pharmaceuticals, a maker of antidepressant pills, paid for the program. It includes a documentary titled "Struggling in Silence" that begins airing on public television stations this week.

"It really has been swept under the carpet," said Dr. Paula Clayton, the suicide foundation's medical director.

The foundation says 300 to 400 doctors commit suicide each year, based on estimates from research, but that more studies are needed to get a more precise count.

Another estimate of 250 yearly comes from an article by Dr. Louise Andrew online and in American Medical News, an AMA publication. But a spokesman said the AMA doesn't track doctor suicides because accurate numbers aren't available.

Suicide figures in broader society are not completely reliable because suicide is often not given as the cause of death.