A remarkable elevation of serum HDL cholesterol concentration (165mg/dl) was found in a 42-year-old Japanese male with chronic pancreatitis who had been cholestatic for several years. An abnormal slow alpha-migrating lipoprotein, larger in particle size and more enriched with cholesteryl ester and apo E than normal HDL, was found in the patient's plasma. Quantitative determination of apo E-rich HDL revealed a striking increase of this lipoprotein in plasma. After choledocho-jejunostomy, a prompt and remarkable decrease of plasma apo E-rich HDL was observed, indicating a direct contribution of cholestasis to the accumulation of apo E-rich HDL in plasma in this patient.