【Abstract】 Objective To observe the acute and delayed antiemetic effects and safety of aprepitant for the prevention of EP regimen chemotherapyinduced nausea and vomiting in smallcell lung cancer patients.Methods 48 patients with smallcell lung cancer were randomly divided into the experimental group and control group, 24 cases in each group. All the patients in the two groups received EP regimen chemotherapy (etoposide and cisplatin). The antiemetic regimen for control group was 5HT3 receptor antagonist tropisetron and dexamethasone. The regimen for experimental group consisted of aprepitant, tropisetron and dexamethasone. The acute and delayed antiemetic effects and adverse effects were evaluated after 1 cycle chemotherapy.Results All the 48 patients completed 1 cycle chemotherapy. The CR rates of acute antiemetic effect in experimental group and control group were 375% and 333%. There was no significant difference between the two groups (P＞0.05). The RR rates of acute antiemetic effect in experimental group and control group were 875% and 792%. There was no difference between the two groups (P＞0.05). The CR rates of delayed antiemetic effect in experimental group and control group were 458% and 167%. There were statistical difference between the two groups (P＜0.05). The RR rates of delayed antiemetic effect in experimental group and control group were 792% and 458%. There was no difference between the two groups (P＞0.05). The adverse effects mainly included dizziness, fatigue, hiccups, bloating and constipation. There was no statistical difference between the two groups.Conclusion Aprepitant combined with tropisetron and dexamethasone has better antiemetic effects on the prevention of nausea and vomiting due to etoposide and cisplatin chemotherapy in smallcell lung cancer patients.