During a five-year prospective study of patient compliance with the Hemoccult slide test as a screen for colorectal cancer, 772 adults above 40 years of age received 1,693 sets of Hemoccult slides. Overall compliance with returning the slides was 75 percent. Compliance remained high with repeat testing. Sixty percent of patients returned all sets of slides. Thirty percent of patients who did not return the first two sets of slide ultimately changed their behavior and returned subsequent slides. Two to five minutes of provider time were required for instruction and distribution of the first set of slides. Distribution of subsequent sets of slides required less than one minute of provider time. Three cancers were detected during the study period. Two of these cancers were diagnosed only by colonoscopy or subsequent surgery and were missed by rigid sigmoidoscopy and barium enema. Stool occult blood screening for colorectal cancer is accepted by patients and requires little physician time in the private practice, fee-for-service setting.