Complications encountered during a typical 12-month period of routine work with the Judkins percutaneous transfemoral method of selective coronary arteriography are reviewed. In 445 examinations, 20 complications (16 local and four cardiac) occurred. Local complications included nine delayed hemorrhages, five thromboses of femoral arteries, and two peripheral emboli. Cardiac complications included one ventricular fibrillation, one significant bradyarrhythmia, and two myocardial infarctions. Causes of individual complications are analyzed and means for their prevention discussed. Guidelines of the procedure are proposed to minimize the complications of selective coronary arteriography. Emphasis is placed on patient evaluation, preparation for the procedure, and meticulous examination technique.