Abstract: The aim of this study was to explore the develompental pattern of liver during neonatal period.Fifteen neonatal pigs were killed and sampled on newborn(day 0),day 3 and day 7 after birth,respectively.A portion of liver tissue was taken for transmission electron microscopic examination.Such biochemical indices as DNA,RNA and liver glycogen were analyzed according to appropriate methods.The hepatocyte cords were arranged in a radial mode and there were abundant mature cellular organelles such as mitochondria and rough endoplasmic reticula in the liver of neonatal pigs.Liver weight increased at a higher rate than body weight in the first 7 days,especially in the first 3 days after birth.Similarly,liver protein content increased significantly in the first postnatal week(P＜0.01).In contrast,liver glycogen content was highest at birth and decreased markedly after birth(P＜0.01).DNA concentration was lowest(P＜0.05) and RNA concentration highest (P＜0.05) in the liver of 3-day old piglets.In conclusion,the hepatocytes of piglets had already developed both in structure and in function at birth.Both the size and the number of hepatocytes increased greatly,and therefore liver grows quickly during the short period after birth.