To assess the immediate and medium term efficacy of percutaneous transluminal coronary angioplasty (PTCA) for restenosis, we retrospectively studied 102 patients undergoing a second PTCA between August 1983 and October 1987. The patients were 89 males and 13 females, mean age 61 +/- 7 years. Before the second PTCA, 13 patients were asymptomatic, 31 had effort angina and 58 resting angina. Exercise stress test performed in 50 patients was positive in 40 cases, negative in 9 and uninterpretable in 1. The coronary lesions were: 59 one vessel disease (58 p. 100) and 43 multivessel disease in which PTCA was performed on 1 lesion in 40 and on 2 lesions in 3. Primary success of PTCA was obtained in 100 patients (98 p. 100); 2 patients underwent coronary artery bypass graft (CABG), 1 as an emergency. At 6 months 45 patients had recurrent chest pain (46 p. 100) and 52 were asymptomatic. Control coronary angiogram performed in 70 patients (72 p. 100) after a mean delay of 7.4 +/- 6 months showed a second restenosis in 34, symptomatic in 31. Medium term follow-up was obtained for 96 patients (96 p. 100) with a mean follow-up period of 22.3 +/- 13.2 months. There were 5 cardiac deaths (5.2 p. 100) and 4 non fatal myocardial infarctions (4.2 p. 100). A new revascularization procedure after the second PTCA was performed in 33 patients (34.4 p. 100). Twenty-five patients underwent a third PTCA (26 p. 100), 5 patients a fourth PTCA (5.2 p. 100) and 11 patients underwent a CABG (11.4 p. 100).(ABSTRACT TRUNCATED AT 250 WORDS)