It's a warm spring night, but Enko N. Kiprilov '00 is sitting in a Harvard classroom watching an instructor solve physics problems on the chalkboard.

The instructor works for Kaplan, the nation's largest test prep company. Kiprilov, who plans to take the MCAT in August, is volunteering his time to try to decide which kind of course he wants to take to get ready.

"The MCAT is going to test your ability to take the MCAT," the Kaplan instructor says. "The key to doing well on the MCAT is practicing." He writes "practicing" in large letters.

Later, Kiprilov says he's decided on a program. "The one I'm planning to take is the most intense," he says.

Kiprilov doesn't doubt that in his four years as a biochemistry concentrator, he's learned a lot about science. Still, it never hurts to be prepared.

"Everybody else is doing it," he says. "Even if you're smart and you know the stuff, it pays to take the course," he says.

Pre-med students know how important the MCAT is to their futures--probably the most important number they will earn at Harvard. For students who plan to go to law school, the LSAT is an equally critical hurdle.

Increasingly, students at Harvard are turning to commercial courses to prepare. Companies like Kaplan and Princeton Review as well as lesser-known competitors offer classes, libraries of old exams and personalized criticism to help defray anxiety--and boost scores.