We clarified the relationship between lipoprotein (a) concentration and restenosis after coronary angioplasty (PTCA). The lipoprotein (a) concentration in patients with restenosis after PTCA was significantly higher than in patients without restenosis after PTCA (33.0 +/- 19.8 mg/dl vs 19.1 +/- 17.4 mg/dl, p less than 0.05]. Moreover, patients with a lipoprotein (a) concentration of more than 30 mg/dl had a high rate of restenosis after PTCA. Restenosis after PTCA is related to lipoprotein (a) concentration.