A serum lipoprotein(a) (Lp(a)) is an independent risk factor for cardiac events. It is well known that the patients with chronic renal failure (CRF) have a high concentration of serum Lp(a). The purpose of this study was to indicate the relationship between serum Lp(a) concentration and apoprotein(a) (apo(a)) isoforms under the condition of renal dysfunction. One-hundred thirty patients having hypertension, hyperlipidemia, diabetes mellitus and/or CRF were selected in this study. All patients were divided into two groups according to the level of serum creatinine. Serum Lp(a) concentration in the CRF patients (Cr > 2.0 mg/dl) was significantly higher than that in the controls (Cr < 1.2 mg/dl). Many CRF patients had high molecular weight (HMW)-apo(a). This study showed that the increase in HMW-apo(a) was closely accompanied by the increase in serum creatinine levels, and the serum Lp(a) concentration with HMW-apo(a) was higher according to their creatinine levels.