Among 868 patients with successful percutaneous transluminal coronary angioplasty (PTCA), 437 were restudied angiographically and had a provocative test with ergonovine during coronary angiography performed before and 6 months after the procedure. The relation between provoked coronary artery spasm and restenosis was studied and 4 groups of patients were analyzed. Those in group 1 (n = 63) had spasm before and after PTCA and their rate of restenosis was high (55%), especially when spasm after PTCA was observed on the dilated coronary segment (restenosis rate 58%). Patients in group 2 (n = 78) had spasm before PTCA but without abnormal vasoconstriction at 6 months and their incidence of restenosis was 19%. Sixty-one patients in group 3 had no spasm before PTCA but developed spasm at restudy. The rate of restenosis was high (38%) in this group, especially when the spasm after PTCA was located on the dilated segment (43%). In group 4 (n = 235), patients had no spasm before or after PTCA and the restenosis rate was 20%. Thus, the presence of coronary artery spasm on the dilated coronary segment, 6 months after a successful PTCA, is frequently accompanied (43% in group 3 and 58% in group 1) by restenosis.