The distribution of cholesterol (C), triglycerides (TG), phospholipids (PL) and protein in the different lipoproteins was studied in male Wistar rats under 2 conditions: control and 2 months after portacaval anastomosis (PCA). PCA decreased the levels of cholesterol and the other components in chylomicrons (-90%), very low density lipoproteins (-65 to -78%), LDL2 (1.040 less than d less than 1.063 g/ml; -51 to -61%) and HDL (1.063 less than d less than 1.21 g/ml), whereas no change was observed in LDL1 (1.006 less than d less than 1.040 g/ml). Apoprotein C contents were decreased in all lipoproteins. The relative proportions of C, TG, PL and proteins in lipoproteins were essentially unchanged by the shunt, suggesting a reduced number of lipoprotein particles in plasma after PCA. It was concluded that PCA reduced the levels of all lipoproteins secreted by liver and/or the intestine without modifying those of intraplasmatic origin (LDL1).