In a double-blind, randomized study, we have compared the efficacy of transdermal hyoscine in the prevention of nausea and vomiting with placebo in 60 young, ASA I-II patients after middle ear surgery during general anaesthesia. In the placebo group, 27% and 43% of patients suffered from nausea and vomiting, respectively, during the first 24 h after anaesthesia. The corresponding values for both symptoms in the hyoscine group were 10% (P < 0.001 between groups). The frequency of side effects was similar in both groups. The results suggest that transdermal hyoscine is a useful prophylaxis against nausea and vomiting after middle ear surgery.