The purpose of this study was to elucidate the possible link between lipoprotein(a) (Lp(a)) and the occurrence of restenosis after initial elective percutaneous transluminal coronary angioplasty (PTCA). Serum lipids, including Lp(a), total cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol, apolipoprotein A-I (Apo A-I), and apolipoprotein B (Apo B), and the Apo B/Apo A-I ratio were examined in 63 consecutive patients (41 men and 22 women, average age 63 +/- 8 years) who underwent initial elective PTCA in our department. Forty two target lesions were in left anterior descending, 10 were in left circumflex and 11 were in right coronary branches. Restenosis was observed in 22 patients (35%) 6.4 +/- 2.6 months after PTCA. The serum Lp(a) level was significantly higher in the restenosis group than in the non-restenosis group (38.0 vs 19.9 mg/dl, p < 0.05). A significant correlation was observed between serum Lp(a) levels and the degree of % restenosis after PTCA (r = 0.557, p < 0.001). However, other lipids showed no significant relationship to restenosis. In addition, the % stenosis before PTCA was found to be related to the occurrence of restenosis after successful PTCA. We conclude that the serum Lp(a) level has a close correlation with the degree of % restenosis after PTCA, and may be a useful index for predicting the possibility of restenosis after PTCA, especially in patients with an Lp(a) level above 30 mg/dl.