OBJECTIVE To compare and contrast the effects of antihypertensive agents on serum lipids and blood pressure in different patient populations. METHODS A MEDLINE search and bibliographies from recent comprehensive reviews were used to identify trials that provided sufficient data to calculate the change in one or more serum lipid values measured before and after antihypertensive therapy. METHODS 474 controlled and uncontrolled clinical trials investigated the effects of 85 antihypertensive agents on lipids and blood pressure in more than 65,000 patients. METHODS Data on triglyceride and total, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol levels; blood pressure; patient characteristics; and study design. RESULTS Differences in the effects of agents, adjusted for differences in patient populations and study design, were examined using multiple linear regression analysis that was weighted by study quality and inverse variance. Diuretics caused relative increases in cholesterol levels (regression coefficient = 0.13 mmol/L; 95% CI, 0.09 to 0.18 mmol/L) that were greater with higher doses (additional effect of high dose, 0.12 mmol/L; CI, 0.04 to 0.20 mmol/L) and were worse in blacks than in nonblacks (additional effect in blacks, 0.13 mmol/L; CI, 0.01 to 0.26 mmol/L). Beta-blockers caused increases in triglyceride levels (0.35 mmol/L; CI, 0.31 to 0.39 mmol/L) that were substantially smaller for agents with intrinsic sympathomimetic activity (amelioration of beta-blocker increase, -0.21 mmol/L; CI, -0.27 to -0.16 mmol/L). When combined with cardioselectivity, beta-blockers with intrinsic sympathomimetic activity favorably affected lipids and reduced both total (-0.14 mmol/L; CI, -0.24 to -0.04 mmol/L) and LDL cholesterol levels (-0.17 mmol/L; CI, -0.28 to -0.07 mmol/L). alpha-Blockers beneficially affected total cholesterol (-0.23 mmol/L; CI, -0.28 to -0.18 mmol/L), LDL cholesterol (-0.20 mmol/L; CI, -0.25 to 0.15 mmol/L), triglycerides (-0.07 mmol/L; CI, -0.11 to -0.03 mmol/L), and, in younger persons, HDL cholesterol (0.02 mmol/L; 0.01 to 0.04 mmol/L). Converting enzyme inhibitors reduced triglycerides (-0.07 mmol/L; CI, -0.12 to -0.02 mmol/L), and, in patients with diabetes, total cholesterol (-0.22 mmol/L; CI, -0.34 to -0.10 mmol/L). Vasodilators reduced total (-0.22 mmol/l; CI, -0.30 to -0.10 mmol/L) and LDL cholesterol (-0.22 mmol/L; CI, -0.29 to -0.11 mmol/L) and increased HDL cholesterol (0.06 mmol/L; CI, 0.02 to 0.09 mmol/L). CONCLUSIONS With the exception of calcium antagonists, nearly all antihypertensive agents affect serum lipids. These effects differ among patient populations.