Back pain. Bad back pain. That's the patient's complaint. As a young doctor-in-training at the UCLA School of Medicine probes the man's lower lumbar area, the sufferer lets out a shriek. Shaken, the second-year medical student turns to an observing physician and asks for help.

The patient is an actor, and the pain and symptoms are faked, but the goal is serious: to teach young doctors how to diagnose and deal sensitively with people in distress. So vivid are the portrayals that the med students often forget they are dealing with actors. "They gasp, stare, call time-outs," says Elizabeth O'Gara, 41, who hires the players for the seven-year-old UCLA program (most U.S. medical schools have adopted similar training). "Or they freeze if they have to tell a cancer victim he's got three months to live." O'Gara's symptomaniacs, culled from a pool of some 300 actors, perform in 15-to-30-minute sessions for 150 students a year, playing victims of everything from date rape to terminal cancer. "It's not like Seinfeld," says O'Gara, referring to a classic episode in which patient-actors try to outdo each other with outrageous symptoms. "They're not supposed to overact. The problem is up to the student to ferret out."

O'Gara was recruited from her previous job as an administrative assistant at the school on the strength of some acting experience. The "patients" she hires earn $25 an hour.

Although O'Gara's audiences may not applaud, they are appreciative. "You're allowed to make mistakes here before you see real patients," says Stacy Thurber, 24, a second-year med student. "Here they can fail safely," agrees O'Gara. "And no one sues for malpractice."