The feasibility of intravascular ultrasound of an intracoronary stent was evaluated in 9 patients (Strecker stent=6 cases and 8 lesions in native coronary arteries; Palmatz-Schatz stent=3 cases and 3 lesions in saphenous vein grafts) who were performed angioplasty repeatedly twice at least. Quantitative and morphologic analyses were performed with an intravascular ultrasound catheter (Diasonics and Boston-Scientific 4.8 F, 20 MHz). The diameter ratio of the stent to native coronary artery was less in the Strecker stent (0.88-0.97) than in the Palmaz-Schatz stent (1.18), as the Strecker stent is unable to expand compared with the Palmaz-Schatz stent whitch is able to change its size. All Strecker stents were restenotic angiographically, and intimal proliferation was noted between stent struts and the native coronary arterial wall compared with the Palmatz-Schatz stent by intravascular ultrasound images. The reason for this finding is that the size of the Strecker stent is easier to reduce than the Palmaz-Schatz stent. (reduction ratio: Strecker=24-35%, Palmaz-Schatz=18%) In conclusion intravascular ultrasound appears to be usefull method for deciding optimal diameter of stent and for evaluating intracoronary stents.