The effect of sulindac on ACE inhibitor-induced cough was studied in eight hypertensive subjects in a randomised placebo-controlled double blind cross-over trial. There was no significant improvement in cough or sense of well-being. Blood pressure, renal function, plasma renin and ACE activity were unchanged. Sulindac however, appears to be effective in some individuals in reducing ACE inhibitor-induced cough with acceptable tolerance and few side effects. Further work is needed to elucidate the mechanism of sulindac's interaction with ACE inhibitors.