In a double-blind, randomized, cross-over study involving 15 mild hypertensive patients, the effects of prazosin (5.7 mg/day) and placebo on plasma levels of lipids, lipoproteins, glucose, and insulin were compared. After 5 weeks of treatment, prazosin had not significantly altered the mean levels of plasma cholesterol, phospholipids, and triglycerides in the high-density lipoprotein or low-density lipoprotein plus very low-density lipoprotein subfractions. Fasting and postload plasma levels of glucose and insulin were also unaffected.