Percutaneous transluminal coronary angioplasty (PTCA) was evaluated as a means of reperfusion of the infarct-related coronary artery, and the results were compared with those of percutaneous transluminal coronary recanalization (PTCR). There were no difference in sex, age, infarct location and time from the onset to start of treatment between 135 patients with evolving acute myocardial infarction treated with PTCA (PTCA group) and 113 patients treated with PTCR alone (PTCR group). Fifty-nine patients in the PTCA group underwent PTCA following PTCR; the remaining 76 patients were without prior PTCR. Successful PTCA, defined as a 20% or more reduction in percent luminal stenosis diameter, was achieved in 123 (90%) of the 135 patients in the PTCA group. The reperfusion rate was 93% in the PTCA group and 77% in the PTCR group (p less than 0.01). Residual stenosis immediately after the treatment was 30 +/- 13% in the PTCA group and 70 +/- 16% in the PTCR group (p less than 0.01). In the PTCA group, three cases developed serious complications which were associated with angioplasty: coronary perforation, side branch occlusion resulting in cardiogenic shock and exacerbation of cardiogenic shock. The latter two patients died, however, there was no difference in hospital mortality rate: 6% in the PTCA group versus 11% in the PTCR group. At follow-up angiography performed four weeks after admission, reocclusion of the successfully recanalized arteries was observed in 3% of the PTCA group and in 14% of the PTCR group (p less than 0.01). Regional wall motion was evaluated by left ventriculography using a wall motion score system which consisted of six grades; from normal counted as 0, to dyskinesis counted as 5. There was no difference in the wall motion score between the successful PTCA group and the successful PTCR group (2.6 +/- 1.4 versus 2.8 +/- 1.4), but the scores of both groups were better than those of the non-recanalized group (3.4 +/- 1.0: p less than 0.01). In conclusion, PTCA and PTCR have the same effect on hospital mortality rate and regional wall motion, but PTCA has a higher reperfusion rate and a lower reocclusion rate than does PTCR. Although PTCA has a potential disadvantage inducing serious complications, it appears to be a useful treatment for acute myocardial infarction.