1. Six healthy volunteers were given single oral doses of the antiemetic metopimazine (MPZ), starting with trial (a) 20 mg preprandially and followed by trial (b) 50 mg preprandially. In trials (c) and (d) the doses were similar to those in trials (a) and (b), but MPZ was given postprandially. To evaluate intra-individual variation in serum concentrations, trial (a) was repeated three times in four of the volunteers (trial (e)). 2. Blood samples were drawn and the serum concentrations of MPZ and its acid metabolite (AMPZ) were measured by h.p.l.c. 3. There was no evidence of dose-dependent kinetics at the dose levels studied. 4. Median AUC values were 22.6, 16.2, 52.4 and 35.2 (trials (a), (b), (c) and (d), ng ml-1 h). Food intake decreased the serum concentrations of MPZ, suggesting that MPZ should be taken preprandially.