We provided a laboratory test program for the personal digital assistant (PDA) to a cohort of third year medical students during their internal medicine clerkship. At the end of each rotation, students were interviewed about their experience with the program, and tracking information was downloaded from their PDAs. Students found the program helpful and easy to use, accessed it more often during patient care activities than as a study aid, and considered the program a better way to learn about laboratory tests than formal teaching sessions. The program was accessed an average of 4 or 5 times per week, although individual use was highly variable. There was no relationship between end-of-clerkship examination scores and the number of tests that were accessed. The PDA program is an effective way to introduce laboratory facts and concepts into an internal medicine clerkship.