In view of the clinical importance of lipoprotein(a) [(Lp(a)] in coronary artery disease (CAD), we investigated the apo(a) size polymorphism, sequence polymorphisms of five base repeats [(TTTTA)n] in the noncoding region, and of Met/Thr in the coding region of the apolipoprotein(a) [apo(a)] gene. The apo(a) polymorphisms were examined in 184 Korean patients with CAD and 121 healthy subjects. In size polymorphism, there was an inverse association between plasma Lp(a) levels and the apo(a) isoforms in the CAD group (p < 0.005). For (TTTTA)n sequence polymorphism, subjects with the 8/8 genotype were most frequently observed in the two groups. Plasma Lp(a) levels showed a significant difference between the 8/5 versus the 8/8 genotype in the CAD group. On the other hand, Lp(a) levels varied significantly among the genotypes of a Met/Thr polymorphism in normal controls (P < 0.01). The heterozygous genotype had an intermediate level of Lp(a) between the two homozygous genotypes, thereby showing gene dosage effect. Thus, it is possible that the apo(a) polymorphisms are responsible for variations in the Lp(a) levels.