We have previously reported on a high prevalence of high renin essential hypertension in psoriasis. Since angiotensin-converting enzyme (ACE) was also reported to be increased in some psoriatics, we found it rational to treat 10 patients with hypertension and diffuse psoriasis with captopril at a dose of 25 mg t.i.d. Five patients had high PRA levels and in 1 of them serum ACE was also increased. Serum creatinine, BUN and urinalysis were normal in all of them. SPB fell from 163 +/- 3 to 138 +/- 3 and DBP from 107 +/- 3 to 86 +/- 2 mm Hg after 1 month of captopril treatment. A surprising clinical improvement of the cutaneous lesions occurred in 3 patients previously resistant to every local or systemic treatment. Unfortunately, however, 3 patients developed heavy proteinuria (greater than 2 g/day) which disappeared after captopril discontinuation. The unexpected incidence of reversible proteinuria induced by low doses of captopril in our patients recommends a careful monitoring of the renal function every time this drug is employed in the treatment of hypertension in a psoriatic.