The activities of the initial enzymes of glycerolipid synthesis were inhibited by the antifertility drug gossypol acetate. Both the dihydroxyacetone phosphate acyltransferase and glycerol phosphate acyltransferase activities of microsomes isolated from liver were inhibited 60% or greater at a concentration of 60 uM. The activity of the peroxisomal dihydroxyacetone phosphate acyltransferase of liver was not greatly affected by gossypol until the peroxisomal activity was solubilized by detergent. It is suggested that gossypol can alter the capacity for glycerolipid synthesis within the microsomal and peroxisomal compartments.