Comparison of lisinopril versus atenolol for mild to moderate essential hypertension. The antihypertensive effects and safety profiles of lisinopril (10 to 40 mg) and atenolol (50 to 100 mg) were compared in a randomized, double-blind, parallel group trial in 144 patients with essential hypertension. After 8 weeks of therapy, seated blood pressure (BP) decreased by 26/15 mm Hg with lisinopril and by 19/14 mm Hg with atenolol. Lisinopril produced a greater reduction (p less than 0.05) in sitting systolic BP than did atenolol. Standing BP decreased by 25/15 mm Hg with lisinopril and by 19/14 mm Hg with atenolol. No important changes in hematologic and biochemical profiles were seen with either drug. Eleven patients, 7 receiving lisinopril and 4 receiving atenolol, were withdrawn because of adverse experiences; another 3 patients defaulted during treatment, 1 in the lisinopril group and 2 in the atenolol group. Both drugs were well-tolerated and are therefore suitable for first-line therapy in essential hypertension. 