In a cross-over study, intravenous diazepam was compared with rectal diazepam for sedation in outpatient oral surgery. Fifty-four operations were performed on 27 patients. Recovery from sedation, experience during the postoperative course, amnesia, estimation of the sedative effect, and patient preference of method of sedation were studied. The recovery times of the sedation methods did not differ. Sedative effects after the first operation were estimated as good by 87% of patients given intravenous sedation and by 75% of those given rectal sedation. However, there was a significant relationship between the subjective experience of stronger sedative effect and preference of sedation method that favored the intravenous technique. The degree of amnesia was significantly higher during intravenous sedation, but a high degree of amnesia was not related to patients' preference for a sedation method. Neither sedation method produced any local side effects.