In a study on 138 hypertensive non-insulin dependent diabetic subjects, factors influencing lipoproteins were assessed. Multiple regression analyses were carried out in order to assess the influence of beta-blocker antihypertensive therapy while making allowances for other confounding variables. In males, but not in females, on a beta-blocker for hypertension, total high density lipoprotein- (HDL-) and HDL-subfraction cholesterol were significantly lower while the serum triglyceride was increased, though not significantly. In male non-insulin dependent diabetics, regimens containing a beta-blocker may worsen an already abnormal lipoprotein profile and antihypertensive agents other than beta-blocking agents should be used if possible.