In a survey of 2,000 physical examinations performed in an internist's office, seven patients with invasive carcinoma of the colon were found. None of the patients in the survey was examined because of large-bowel symptoms. All seven patients had positive tests for occult blood in at least one of three stool specimens. This finding led to the preparation of an easier method for multiple stool examination as a routine office procedure. Recent reports have emphasized the limitations of the sigmoidoscope in cancer detection. If a positive reaction is obtained from a multiple stool occult blood test, the patient should be further examined with barium sulfate enema roentgenograms. This is one of the best methods for detecting large-bowel cancer during routine well-patient examinations.