This study was undertaken to determine the pattern of changes in serum protein and lipoproteins in pregnancy. We have measured lipoprotein composition in age-matched non-pregnant and pregnant women(month 2, 3, 5, 9 and 10). The results are as follows: 1) Serum protein and protein content in HDL were higher and those in VLDL and LDL were lower in early pregnancy compared to non-pregnant women and all become similar to non-pregnant women in late pregnancy. 2) Serum cholesterol and cholesterol content in VLDL were higher until late preanancy and those in LDL and HDL were lower in early pregnancy and belome similar to non pregnant women in late pregnancy. 3) Serum phospholipid and phospholipid lontents in VLDL and LDL except in HDL increased during pregnancy. 4) Serum triglyceride and triglyceride contents in HDL and LDL except VLDL increased markedly during pregnancy. In conclusion the huperlipidemia of pregnancy is well recognized although the mechanisms responsible for its development remain unknown and need to be investigated further.