BACKGROUND: Mu-receptor antagonists are considered effective for the treatment of epidural morphine induced pruritus (EMIP). However, they have been associated in certain cases with a concomitant reduction in analgesia. It is noteworthy that propofol has been shown to produce marked spinal depression, in particular of the dorsal and ventral horn. Recently it was reported that subhypnotic doses of propofol were efficient in relieving EMIP. This study was designed to investigate an effective minimum dose of propofol. METHODS: After obtaining informed consent from patients and with IRB approval, 155 patients having cesarean section received an epidural morphine 3 mg bolus, and 4 mg/day with continuous infusion for 2 days via a Baxter infusor(R). Patients who had pruritus with scratching were allocated randomly to one of the three groups. Patients received 10 mg propofol intravenously in group I (n = 25), 20 mg in group II (n = 25) and 30 mg in group III (n = 25). Pruritus and the level of sedation were assessed 5 minutes later using 5 points pruritus rating scale (PRS) and 4 points sedation rating scale (SRS). Statistical analysis was performed using chi-square test, one-way ANOVA and paired t-test. P < 0.05 was considered significant. RESULTS: Seventy-five patients showed pruritus with scratching (PRS > or = 3). The success rate was significantly greater in the group II (76%) and group III (80%) than in the group I (48%) (P < 0.05). Seven patients had an increase in sedation in the group III versus none in the group I and group II (P < 0.05). The beneficial effect of treatment was longer than 60 minutes in 100% of patients in group I, II and III. CONCLUSION: These results suggest that 20 mg propofol and 30 mg propofol intravenously are equally effective in treating EMIP than 10 mg propofol. However the level of sedation is significantly less in 20 mg propofol group than 30 mg propofol group.