The effect of antihypertensive drugs on lipoprotein subfraction profile is still under investigation. In this study the effects of fixed combination of valsartan with either amlodipine (V --A) or hydrochlorothiazide (V --H) on low-density-lipoprotein (LDL) and high-density-lipoprotein (HDL) subfraction profile of patients with stage 2 or 3 hypertension were assessed. A total of 60 drug-naive patients were randomized to either V --A (160/5 mg, n ¼ 30) or V --H (160/12.5 mg, n ¼ 30). At baseline as well as 16 weeks post-treatment analysis of the LDL and HDL subfraction profile was conducted by using LDL Lipoprint System. Both V --A and V --H effectively reduced blood pressure (BP) to similar levels. An increase in the cholesterol concentration of small-dense LDL subfractions (by 18.2%, Po0.05) was observed in the V --H group, whereas this parameter remained unchanged in the V --A group. Therefore, mean LDL particle size was decreased in the V --H group (from 267 ± 5 to 266 ± 5Å, Po0.05). HDL-Cholesterol (HDL-C) levels were reduced by 4.7% (Po0.05) in the V --H group, mirrored by a reduction in the cholesterol mass of small and intermediate HDL particles. In conclusion, despite similar reductions in BP, V --H combination may adversely affect serum lipids as well as LDL and HDL subfraction profile as compared with V --A.