The feasibility and applicability of intravascular ultrasound (IVUS) of the coronary arteries were evaluated in 65 patients undergoing 70 coronary interventional procedures. Morphologic and quantitative analyses were performed with a mechanically rotated IVUS catheter (4.8Fr, 20 MHz) and with orthogonal view cineangiography. A semiautomated edge-detection algorithm was used for cineangiographic quantification. Coronary interventions included 45 percutaneous transluminal coronary angioplasties, 9 excimer lasers, 11 directional coronary atherectomies, 3 rotational atherectomies and 2 stents. Most lesions consisted of a mixture of plaque composition (hard, n = 30; soft, n = 64). Other unique morphologic data by IVUS were plaque topography (eccentric, n = 34; concentric, n = 36) and vessel dissection (IVUS [n = 29] versus angiography [n = 14], p less than 0.05). Postprocedure minimal lumen diameter and cross-sectional area measured by IVUS were larger and poorly correlated with angiography (r = 0.28, standard error of the estimate = 0.52 mm; r = 0.08, standard error of the estimate = 1.0 cm2, respectively). IVUS is more sensitive than angiography when assessing postintervention lesion characteristics including vessel dissection and plaque morphology. Catheter-based ultrasound appears to be a useful adjunct to contrast angiography when evaluating and comparing the therapeutic impact of conventional percutaneous transluminal coronary angioplasty with new technologies.