There are a number of potential causes for false-positive results on a barium enema study. We report three cases in which patients had to have colonoscopy because a nifedipine slow-release tablet (Procardia XL) was misinterpreted as a colonic polyp on a barium enema study. The pill did not move with abdominal compression, further suggesting that it was a polyp. Patients in whom similar lesions are identified during barium enema examination should be questioned as to whether they are taking these medications. © 1994 Southern Medical Association.