The effect of bezafibrate on plasma lipids, lipoproteins, apolipoproteins AI, AII and B, and LCAT activity was investigated in 16 hyperlipidemic, non-insulin-dependent diabetes, who were treated for 8 weeks with either placebo or bezafibrate in a double-blind cross-over design. Bezafibrate induced a significant decrease in plasma triglycerides (P less than 0.01), cholesterol (P less than 0.05), VLDL triglycerides (P less than 0.05) and VLDL cholesterol (P less than 0.01), and a significant increase in HDL cholesterol (P less than 0.01), whereas LDL cholesterol remained unchanged. The apolipoprotein AI/apolipoprotein B ratio increased significantly (P less than 0.05), although individual changes in these apolipoproteins were not significant. Apolipoprotein AII increased significantly (P less than 0.05), although individual changes in these apolipoproteins were not significant. Apolipoprotein AII increased significantly (P less than 0.0001) and the apolipoprotein AI/apolipoprotein AII ratio decreased (P less than 0.0001), indicating an increase in the HDL3 rather than the HDL2 fraction. No significant change in LCAT activity was observed.