The efficacy and safety of coronary angioplasty for stenoses adjacent to coronary aneurysms were studied in 25 patients (19 men and 6 women, mean age 62 +/- 11 years). The study represented 1.1% of patients undergoing coronary angioplasty during the study time period. The aneurysm diameter exceeded 1.8 +/- 0.2 times the normal artery diameter. Eleven (44%) of these aneurysms were localized in the left anterior descending, 3 (12%) in the circumflex and 11 (44%) in the right coronary artery. Percent diameter stenosis was reduced from 72 +/- 10% to 23 +/- 19%, and transstenotic gradient from 51 +/- 13 to 15 +/- 9 mmHg when measured. Clinical success (absence of pain on discharge without coronary bypass surgery, death, or infarction) was achieved in 24 (96%) patients. In one patient acute vessel closure occurred. No embolic events or coronary artery rupture occurred. Seventeen (71%) of the 24 successful patients remained asymptomatic at clinical follow-up (mean = 7.7 +/- 5.0 months). At late follow-up, one patient had sustained a myocardial infarction, two had elective bypass surgery, and two had successful repeat angioplasty. The data from this small patient population suggest that angioplasty for a stenosis adjacent to a coronary aneurysm can be performed safely with a high primary success rate.