We investigated the effects of aggressive antihypertensive therapy based on hydrochlorothiazide, candesartan or lisinopril on left ventricular mass (LVM) index and arterial stiffness in hypertensive type II diabetic individuals. Seventy hypertensive type II diabetic individuals were treated with three antihypertensive strategies in a randomized, double-blind, double-dummy design. Blood pressure was titrated to levels below 130/85 mm Hg or a decrease in systolic pressure of 10% with a diastolic pressure below 85 mm Hg. After titration, patients were treated for 12 months. Mean blood pressures were 157/93, 151/94 and 149/93 mm Hg at baseline in the hydrochlorothiazide (n = 24), candesartan (n = 24) and lisinopril (n = 22) groups, and 135/80, 135/82 and 131/80 mm Hg after titration. About 70% reached target blood pressures, with the median use of three antihypertensive drugs. Left ventricular mass index and all estimates of arterial stiffness showed significant improvement after 12 months: that is, LVM index (-11 g/m(2); -8%); carotid distensibility coefficient (DC; +2.8 x 10(-3) kPa(-1); +27%), compliance coefficient (CC; +0.13 mm2/kPa; +21%) and elastic modulus (-0.19 kPa; -16%); femoral DC (+1.6 x 10(-3) kPa(-1); +50%) and CC (+0.08 mm2/kPa; +26%); brachial DC (+2.1 x 10(-3) kPa(-1); +39%) and CC (+0.03 mm2/kPa; +27%) and total systemic arterial compliance (+0.29 ml/mm Hg; +16%). No differences in outcome variables between treatment groups were observed. Aggressive antihypertensive treatment, although difficult to achieve, resulted in substantial reductions of LVM index and arterial stiffness in relatively uncomplicated hypertensive type II diabetic individuals. Strategies based on renin-angiotensin system inhibitors were not clearly superior to conventional (i.e. diuretic-based) strategies.