This study investigated the safety and efficacy of doxazosin treatment in a large population of patients (n = 336) with essential hypertension and assessed the effect of doxazosin on the serum lipid profile and the calculated risk of developing coronary heart disease. Patients were assigned to two groups: those with a baseline diastolic blood pressure greater than or equal to 95 mm Hg (group 1) and those with a baseline diastolic blood pressure less than 95 mm Hg (group 2) that was controlled by previous antihypertensive therapy. Doxazosin treatment (monotherapy in 76.2% of patients) significantly (p less than 0.05) reduced the blood pressure of patients in group 1 (-23/-17 mm Hg) after 10 weeks and maintained the control of blood pressure for patients in group 2. Heart rate was essentially unchanged in both groups. Mean final daily doses of 3.6 and 3.2 mg were achieved in groups 1 and 2, respectively. Treatment with doxazosin improved the severity category of hypertension for 88.4% of patients in group 1; 87.3% of patients were considered a therapy success. Doxazosin had a favorable effect on the serum lipid profile in both groups of patients. The majority of lipid changes achieved statistical significance and resulted in a significant 27% decrease in the calculated risk of developing coronary heart disease. Doxazosin was well tolerated; only 24.1% of patients had side effects that were related or possibly related to treatment. In nine (2.7%) patients the dose of doxazosin was reduced and 26 (7.7%) patients withdrew from doxazosin therapy because of side effects.