BACKGROUND: The gold standard test for the diagnosis of coronary artery disease (CAD) is conventional coronary angiography (C-CAG). Lately, multislice computed tomographic coronary angiography (MSCT-CAG) demonstrated a high sensitivity and a negative predictive value for a CAD primary diagnosis when compared with C-CAG. The aim of our study is to prospectively assess the safety of ruling out CAD based solely on a normal MSCT-CAG result. METHODS: From June 15, 2004, to January 20, 2006, consecutive patients initially scheduled for C-CAG for a primary diagnosis of CAD underwent MSCT-CAG instead. Patients with a highly calcified coronary network or with an abnormal or a noninterpretable MSCT-CAG result underwent secondary C-CAG and were excluded from the study. We included patients whose diagnosis of CAD was ruled out by a normal MSCT-CAG result; in those patients, C-CAG was not performed. All patients underwent further follow-up with clinical end points (death, subsequent C-CAG, and myocardial infarction). RESULTS: In 141 patients, MSCT-CAG results were considered normal. During the follow-up period (mean, 14.7 months), those patients experienced 0% mortality, a 3.5% rate of subsequent C-CAG, and a 0.7% rate of myocardial infarction. The risks of subsequent death, new referral for C-CAG, or coronary events compare favorably with those following normal C-CAG, which were 0.4%, 4.3%, and 0.6%, respectively. CONCLUSIONS: Multislice computed tomographic CAG safely rules out CAD in patients with suspected disease and allows patients to be managed less invasively, by reducing the number in whom C-CAG has to be performed.