The safety and short-term therapeutic benefit of multilesion percutaneous transluminal coronary angioplasty was assessed in 135 patients, 66 of whom had a minimum of 6 months of follow-up study. Primary success, defined as successful dilation of the most critical lesion or all lesions attempted without major in-hospital complications was obtained in 117 (87%) of the 135 patients. Cardiac complications associated with the procedure were uncommon; prolonged angina occurred in 5% and myocardial infarction in 3%; emergency coronary bypass surgery was performed in 4% of the patients. There were no deaths. Complete revascularization was achieved in 46% of the 117 patients with a primary success. Of the 66 patients eligible for 6 month follow-up, 80% had an uncomplicated course and required no further procedures. Clinical improvement by at least one angina functional class was observed in 90% of the patients. Cardiac events such as the need for a second revascularization procedure were significantly more common in patients who had incomplete versus complete revascularization (35 versus 9%; p = 0.018). Repeat coronary angiography performed an average of 5 months after angioplasty revealed restenosis in 18 of 22 symptomatic patients and 3 of 9 asymptomatic patients. Restenosis occurred at the site of a single dilation in 12 patients, at two sites in 8 patients and at three sites in 1 patient. Thus, multilesion coronary angioplasty is an important therapeutic option for selected patients with multivessel disease and can be performed with relatively low risk. Improvement in angina status can be expected even in patients who have incomplete revascularization.(ABSTRACT TRUNCATED AT 250 WORDS)