Coronary artery disease is the major cause of death in diabetic renal transplant recipients. Because one-third of diabetic transplant candidates have clinically silent coronary artery disease, many transplant centers recommend coronary angiography prior to transplantation. However, angiography is expensive and may precipitate acute renal failure. Therefore, we developed a noninvasive screening algorithm to identify patients at low risk for coronary artery disease (CAD), defined as one or more coronary stenoses > or = 50% diameter. We performed coronary angiography in 141 consecutive asymptomatic Caucasian type I diabetic renal transplant candidates. Fourteen of 16 patients age 45 or older had CAD. One hundred and twenty-five patients under age 45 were randomly divided into two groups. Ninety patients were used to identify clinical factors significantly associated with CAD which included smoking for five or more pack years, nonspecific ST-T wave changes on electrocardiogram, and diabetes duration 25 years or longer. The screening algorithm, "CAD is predicted in diabetic transplant candidates under age 45 with any of the above risk factors," was then tested in the remaining 35 patients and in 35 additional patients. In these 70 patients, the algorithm had a sensitivity of 97% and a negative predictive accuracy of 96%. We conclude that coronary angiography should be recommended to Caucasian type I diabetic renal transplant candidates age 45 or older because of the high probability of disease. In patients younger than 45 without a smoking history, ST-T wave changes on EKG, or diabetes longer than 25 years, the likelihood of CAD is low and angiography can be avoided.