The addition of doxazosin to the treatment regimen of patients with hypertension not adequately controlled by beta-blockers. When doxazosin was given to patients with hypertension not adequately controlled by beta-blockade, blood pressure was normalized in 94% of the 34 patients (blood pressure less than or equal to 140/85 mm Hg). This reduction in blood pressure was obtained with doxazosin in combination with metoprolol or oxprenolol at a mean final daily dose of 1.3 mg or pindolol or atenolol at 2.0 mg/day. Exercise-induced increase in systolic and diastolic blood pressure was also lower with combined beta-blocker and doxazosin therapy than with beta-blocker alone. After 12 weeks of treatment, the combination of doxazosin and beta-blocker significantly reduced total serum cholesterol and triglyceride levels. All side effects were mild and only one patient was withdrawn from therapy. 