ABSTRACTBlack pepper, its oleoresin or its active principle piperine fed to rats at doses 5 to 20 times normal human intake did not cause any adverse effect on: (1) growth, food efficiency ratio and organ weights; (2) RBC, WBC and differential counts; (3) the levels of blood constituents like hemoglobin, total serum proteins, albumin, globulin, sugar and cholesterol; (4) the levels of serum aminotransferases and phosphatases and (5) fat and nitrogen balance.