Primary care physicians, including family physicians, often perform flexible sigmoidoscopy in their clinical practices. It is unknown how many of these and other endoscopic procedures, such as esophagogastroduodenoscopy and colonoscopy, are performed by these physicians. Therefore, physician reimbursement by the Medicare program was documented for selected endoscopic procedures during the calendar year 1993. Family physicians and general practitioners in the United States were reimbursed for 125,821 flexible sigmoidoscopies, 21,070 upper gastrointestinal tract endoscopic procedures, and 23,841 colonoscopies. General internists performed considerably more endoscopic procedures than did family physicians. Primary care physicians performed 44% of the reimbursable flexible sigmoidoscopies, 17% of upper gastrointestinal tract endoscopies, and 15% of colonoscopies in this patient group. In 1993, primary care physicians generated a total of $175 million in allowed charges by the Medicare program for gastrointestinal tract endoscopic procedures, of which $22.6 million was to general practitioners and family physicians. Family physicians, on average, charged less for gastrointestinal tract endoscopic procedures than did other physician specialists. Primary care physicians, especially general internists, are providing substantial numbers of gastrointestinal tract endoscopic services to their patients. As Medicare does not generally reimburse physicians to perform flexible sigmoidoscopy for colorectal cancer screening, it is likely that primary care physicians performed considerably more procedures than were documented in this study.