The role of 16-slice spiral CT was evaluated in the diagnosis of coronary stenosis, with selective X-ray coronary angiography (SCA) serving as the reference standard. Sixty-five patients who were suspected of having coronary heart disease, without percutaneous transluminal coronary angioplasty or coronary bypass-grafting, were investigated using 16-slice CT. Eight patients with pre-scan heart rate of more than 80 beats/min were given beta-blockers. After the retrospectively ECG-gated axial imaging reconstruction, volume redering (VR), multi-planar reconstruction (MPR), curved MPR and maximum intensity projection (MIP) were used to reconstruct. Every segment of coronary artery with a diameter > or = 1.5 mm was assessed, and the presence on CT with a stenosis exceeding 50% diameter reduction was compared with that on SCA. The reasons which lead to some segments unevaluable were analysed. Compared with SCA, 93% coronary segments and 94% main branches were evaluable. Residual cardiac motion artifacts, severe calcification and poor opacification made 58%, 28% and 14% of the remaining 60 segments unevaluable respectively. Without routine administration of beta-blockers, good coronary imaging quality can be acquired using 16-slice spiral CT. It is a reliable noninvasive method for detection of obstructive coronary artery disease.