The authors evaluated use of seven cancer screening tests by 52 providers in a university general internal medicine practice, using 1980 American Cancer Society (ACS) recommendations as standards for comparison. Performance rates were determined by retrospective medical record reviews of a stratified random sample of 525 patients. In addition, the 48 physicians and four nurse-practitioners in the practice were interviewed to determine their opinions, knowledge and perceived use of the tests. Performance rates were low, significantly below the ACS guidelines for all tests except Pap smear. Providers used the tests significantly more often to evaluate patients with cancer risk factors or for new patients. They significantly overestimated their own performances of six tests. More than a fourth of the providers disagreed with the use of mammography, sigmoidoscopy, pelvic or rectal examinations for screening asymptomatic adults. Their knowledge about cancer screening and the ACS recommendations was highly variable, and frequently quite limited. Providers offered four major reasons for not performing the screening tests: provider forgetfulness, lack of time, inconvenience and logistical difficulties, and patient discomfort or refusal.