The antihyperlipidaemic property of a hydroalcoholic extract obtained from the leaves of Croton cajucuru Benth. (Euphorbiaceae) was studied in rats fed a high fat diet. Ten weeks following daily oral administration of plant extract (200 mg/kg), significant reductions in the serum total cholesterol (Tc), and low-density lipoprotein cholesterol (LDL-c) levels were observed without much change in serum high-density lipoprotein cholesterol (HDL-c) and triglycerides. The data also showed a significant elevation in the HDL-r/Tc ratio in plant extract treated rats compared with the control group. The atherogenic index was significantly decreased by extract treatment. These beneficial effects and the absence of acute toxicity in C. cajucara extract may be of significance in the treatment of atherosclerosis.