The hypocholesterolaemic effect of Cassia fistula was investigated using hypercholesterolaemic male albino rats. Hypercholesterolaemia was induced by feeding on a mixture of cholesterol plus cholic acid for a 12 weeks period. Hypercholesterolaemia was characterized by significant increase in the average levels of total lipids, total cholesterol, and triglycerides and significant decrease in phospholipids content. Administration of Cassia fistula significantly reduced blood and liver total lipids. Brain, spleen, kidneys and heart followed nearly the same trend but with moderate effect. Blood, liver, kidneys, spleen and heart total cholesterol was significantly reduced, while that of brain was not affected. The level of triglycerides was markedly improved. There was a moderate rise, however, in phospholipids content in all studied organs. That is to say a marked progress in the correction of lipid metabolism occurred. Also, administration of Cassia fistula induced a significant decrease in the high activities of serum GOT, GPT, alkaline and acid phosphatase and the values nearly returned the initial values. Total serum protein, albumin (A), globulin (G), A/G, free amino acids, uric acid and creatinine were also determined and their values were improved and attained nearly the normal values of the control group.