Our study suggests that the antiemetic efficacy provided by concurrent dexamethasone and ramosetron prophylaxis is superior to ramosetron alone. Our results showed that prophylaxis with dexamethasone and ramosetron was more effective than ramosetron alone in decreasing the incidence and severity of PONV, the rescue antiemetic requirement, and in obtaining a higher complete response during the first 6 hours and during the entire 72-hour study period. Our findings concur with those of previous studies showing the superior antiemetic effect of concurrent dexamethasone and 5-HT3 antagonist to the 5-HT3 antagonist alone [21, 22], but no previous study has investigated the antiemetic efficacy of concomitant dexamethasone and ramosetron after TKA. Two previous studies reported that ramosetron monoprophylaxis after TKA provided a limited antiemetic effect during the 2- to 48-hour or 6- to 48-hour period compared with ondansetron or no prophylaxis