Objective To evaluate the distribution pattern of apolipoprotein(a) [Apo(a)] phenotypes in Koreans and the effect of dialysis modality on serum lipoprotein(a) [Lp(a)] concentration according to apo(a) phenotype in patients with end-stage renal disease (ESRO). Design Cross-sectional study. Setting A university hospital. Participants: 153 normal controls, 99 hemodialysis (HO) patients and 82 continuous ambulatory peritoneal dialysis (CAPO) patients. Main Outcome Measures Fasting serum Lp(a), lipids, and apo(a) phenotypes were measured. Results The frequencies of the subjects with apo(a) phenotypes of high-molecular weight only, including S3, S4, or S5 or null type were 95.4% of control, 100% of HO patients, and 95.1% of CAPO patients. The frequent apo(a) phenotypes in Koreans consisted of S4, S4S5, S5, and S5S5 isoforms. Significant difference was found in serum Lp(a) concentration among controls and HO and CAPO patients [median (interquartile range): 0.05 g/L, (0.01 0.19); 0.19g/L, (0.10 0.35); 0.63g/L, (0.28 0.90), p< 0.001]. Lp(a) levels in CAPO patients were significantly higher than in HO patients for all four common apo(a) isoforms found in Korean subjects. CAPO patients had higher total and LOL cholesterol levels, and higher ApoB levels than H O patients. Significant differences were found in serum albumin levels between controls and HO and CAPO patients (44 ± 3 g/L, 40 ± 4 g/L, 32 ± 7 g/L, respectively, p < 0.05). There were significant inverse correlations between serum albumin and Lp(a) (r = -0.33, p < 0.01), total cholesterol (r = -0.31, p < 0.01), LOL (r = -0.39, p < 0.01) or ApoB (r = -0.35, p < 0.01) in ESRO patients. A significant positive correlation was found between serum albumin and ApoA1 (r = 0.24, p < 0.01). Conclusion These findings indicate that Koreans have mainly high -molecular weight apo(a) phenotypes and serum Lp(a) is elevated in CAPO patients compared to HO patients for common apo(a) phenotypes, which may contribute to the frequent cardiovascular mortality in CAPO patients.