Using the molecular sieve high performance liquid chromatography (HPLC), we analyzed human serum apolipoproteins and attemped to isolate them. The apolipoproteins obtained from human serum very low-density lipoproteins (VLDL), high-density lipoproteins (HDL) and lipoprotein depleted serum were chromatographed on TSK G3000SW column. HPLC was performed in 6M urea (pH3.15) or 0.1M Tris-buffered 4M guanidine hydrochloride (pH7.0). As a result, better separation of apoproteins were achieved using 4M guanidine hydrochloride as an elution buffer. By this technique, apo VLDL could be separated into three peaks of apo B, apo E and apo C, apo HDL into apo E, apo A-I, apo A-II and apo C, and the apoproteins of d>1.21g/ml fraction into albumin, apo A-IV and apo A-I. Pure materials of apo E, apo A-I and apo A-IV could be obtained by a single column operation.