The effects of pretreatment with enalapril, and sulindac, on the weal response to intradermal injections of substance P and neurokinin A were assessed in a randomised, double-blind, placebo-controlled study. Weal responses to both substance P and neurokinin A depended significantly on dose. Neither enalapril nor sulindac, nor the combination of these agents influenced the responses to either tachykinin. These results do not suggest any role for substance P or neurokinin A in the clinical effects of angiotensin converting enzyme inhibitors.