Human serum high density lipoprotein was isolated by a process of sequence ultracentrifugation, yielding a single band on 0.5% agarose gel electrophoresis and contained no albumin. The highdensity lipoprotein was delipidated and fractionated by sephadexG—200 chromatography into four peaks. The 2nd peak was taken and isolated by DEAE—52 ionexchange chromatography. The apolipoprotein A—I was shown to be pure, which yielded a single band with a molecular weight 28000 when analyzi...