Previous studies have indicated that inhibitors of angiotensin converting enzyme (ACE) enhance the immune response and make patients more sensitive to allergens, We have studied the effects of ACE inhibitors on skin test reactivity. 20 patients with cough (Group 1) and 20 patients without cough (Group 2) treated with an ACE inhibitor for essential hypertension and 20 healthy control subjects (Group 3) were included. The subjects were tested with common aeroallergens. There was no significant difference between Group 1 and 2 subjects. However, there was a significant difference in skin test reactivity between Group 1 and Group 3 individuals as well as between Groups 2 and 3 (P < 0.05 respectively). We conclude that ACE inhibitors enhance skin test reactivity. Med Sci Res 27:305-306 (C) 1999 Lippincott Williams & Wilkins.