Over a 5 year period at three centers, 53 patients underwent percutaneous transluminal angioplasty of a right coronary artery ostial stenosis. The procedure was successful in 42 patients (79%) and unsuccessful in 11, of whom 5 (9.4%) required emergency coronary artery bypass grafting because of abrupt closure. The right coronary ostial lesion had distinctive technical requirements to achieve success, including high pressure balloon inflation (10 +/- 4 atm) and the need for unconventional right coronary guide catheters. Technical factors that account for increased difficulty in these patients include: problems with guide catheter impaction and ostial trauma; inability to inflate the balloon with adequate guide catheter support; and need for increased intracoronary manipulation. The stenoses were quite discrete (4 +/- 5 mm) and calcified in the majority (40) of the 53 patients. Long-term follow-up (mean 12.5 months, range 4 to 60) of these patients demonstrated clinical recurrence of angina in 20 patients (48%) and angiographically proved restenosis in 16 (38%). Repeat coronary angioplasty was successful in three of six patients for relief of symptoms for over 6 months. In conclusion, angioplasty of the right coronary ostial lesion compared with nonostial dilation leads to a suboptimal early success rate; an apparent high risk of emergency bypass surgery; and a high restenosis rate. Careful assessment of the patient with this lesion and improved technology appear to be warranted.