OBJECTIVE To examine whether physician background and attitudes were altered to the decision to refer a patient with chronic angina to a cardiologist following the results of an exercise tolerance test. DESIGN Mailed questionnaire asking family physicians and internists how they would make referral decisions for a patient with classic angina in a detailed case vignette. PARTICIPANTS Two hundred sixty-five family physicians and 105 internists. OUTCOME MEASURES Physician referral decisions following results of an exercise tolerance test. RESULTS Only 15% of the respondents believed that the patient should have been directly referred for cardiac catheterization without conducting an exercise tolerance test previously. Data on the remaining 85% of physicians were analyzed to identify factors influencing referral decisions. These physicians were significantly more likely to refer a patient if they were concerned about a lawsuit (68% vs 53% following a test result suggesting coronary disease and 40% vs 24% following a normal test result). Referral decisions were significantly more likely to be changed on the basis of the test result if the test was administered to determine the need for cardiac catheterization (50% vs 34%) or if the physician was a family practitioner rather than an internist (47% vs 24%). A physician's number of years in practice, experience with patients with angina, and board certification were not associated with referral decisions. CONCLUSIONS Many physicians with very different attitudes and backgrounds order diagnostic tests for reasons other than to make referral decisions. This problem appeared to be less prevalent among family physicians than internists, and it may partly be due to fear of lawsuits or lack of knowledge about how the test should be used.