1 The antihypertensive effect and tolerability of MK‐196 (10 mg and 15 mg daily) was compared to hydrochlorothiazide (HCT; 50 mg daily) in a 4‐ week multiclinic, double‐blind study involving 42 patients with mild to moderate, essential hypertension. 2 Both doses of MK‐196 were as effective and sometimes more effective than HCT in lowering standing and supine systolic and diastolic blood pressures. 3 HCT consistently brought about significant increases in serum uric acid and significant decreases in serum potassium; both doses of MK‐196 produced similar but less frequent and smaller changes in both of these parameters. 4 Both doses of MK‐196 brought about significant decreases in body weight at Weeks 3 and 4 of drug treatment. 5 Patients taking MK‐196 reported fewer adverse clinical reactions (10 mg = 15%; 15 mg = 13% than those taking HCT (21%). 6 MK‐196 may offer a therapeutic advantage over HCT as an antihypertensive agent for use in the treatment of mild to moderate, essential hypertension.