Abstract. In order to ensure the continuity of chemotherapy, it is crucial to provide appropriate supportive care to prevent chemotherapy-induced nausea and vomiting (CINV). The frequency of CINV is greatly affected by the type and combination of chemotherapy employed, which requires further investigation. With the use of patient diaries, a prospective study on the efficacy of antiemetic regimens for nausea and vomiting was conducted in 103 patients receiving highly or moderately emetogenic chemotherapy in the Ambulatory Therapy Center of our institution between August, 2010 and March, 2011. In this study, the efficacy of palonosetron in the delayed phase was affirmed. On days 4 and 5, in particular, palonosetron exhibited a significantly higher efficacy compared to that of other conventional serotonin (5-HT 3 ) receptor antagonists (5-HT 3 RAs). When the effects of chemotherapy on food intake were assessed by switching granisetron to palonosetron, an improvement in appetite was observed in one-quarter of the cases in the delayed phase. In addition, palonosetron has not been associated with any severe adverse drug reactions. It was therefore suggested that the use of palonosetron be recommended as a 5-HT 3 RA. In conclusion, our data suggested that palonosetron is effective and may be used as a 5-HT 3 RA, since it is crucial that we take adequate measures against CINV in order to maintain the patients' quality of life and to develop antiemetic regimens that ensure the continuity of chemotherapy without dose reduction.