BACKGROUND. Despite current recommendations of flexible sigmoidoscopy as a screening test for the detection of colorectal carcinoma, relatively few asymptomatic patients undergo this procedure. To enhance the use of sigmoidoscopy, differences in the use of screening, as well as barriers to screening among specific physician groups, should be defined. METHODS. The authors surveyed 1762 practicing primary care physicians to determine their self-reported ability to perform sigmoidoscopy and perceived obstacles to either initiating or enhancing screening. RESULTS. A total of 884 physicians (50%) responded. Ninety percent of primary care physicians reported that they offered sigmoidoscopic screening to their patients, with 46% referring patients and 44% performing the procedure themselves. Physician characteristics were not associated with the overall use of sigmoidoscopy. In contrast, compared with physicians who referred patients for the procedure, physicians who performed sigmoidoscopy themselves were more often board certified, male, and graduated from medical school after 1970 (P < 0.001). In a multivariate analysis, these characteristics were also independently associated with the ability to perform sigmoidoscopy. The barrier to sigmoidoscopy cited most often was poor patient acceptance, whether or not the physician performed or referred patients for sigmoidoscopic screening. Other barriers cited were lack of training, lack of equipment, and time required, each of which was identified most often by physicians who did not screen at all. CONCLUSIONS. Most physicians surveyed reported using sigmoidoscopic screening to some degree in their practice, although many did not perform the procedure themselves. Population-based interventions to increase screening may benefit from targeting specific physician subgroups and attempting to improve patient acceptance of the procedure.