Aims: To determine the antiemetic efficacy of a 6-day aprepitant schedule in patients receiving multipleday cisplatin. Patients & methods: Patients diagnosed with lung cancer and who were chemotherapy naive were screened. The patients willing to use aprepitant were randomly divided into two groups: prolonged use of aprepitant (PA; 6-day aprepitant) and standard use of aprepitant (SA; 3-day aprepitant); the patients who rejected aprepitant were recruited into the control group (group C). Primary end points included the safety and the number of days without chemotherapy-induced nausea and vomiting. Results: There was no statistical difference in adverse events among the three groups. The average days without chemotherapy-induced nausea and vomiting of group PA (18.28 +/- 3.35) was significantly longer than in groups SA and C. Furthermore, better life function scores were achieved in group PA according to the Functional Living Index - Emesis questionnaire. Conclusion: In this study 6-day aprepitant was safe and more effective than standard 3-day aprepitant in controlling chemotherapy-induced nausea and vomiting due to 3-day cisplatin regimens. Plain language summary: The aim of this study was to determine the effectiveness of a 6-day aprepitant schedule in patients receiving a multiple-day highly emetogenic chemotherapy drug (cisplatin). Aprepitant is an important medication used to prevent chemotherapy-induced nausea and vomiting (CINV). The patients willing to use aprepitant were randomly divided into two groups: prolonged use of aprepitant (PA; 6-day aprepitant) and standard use of aprepitant (SA; 3-day aprepitant). The patients who rejected aprepitant were recruited into the control group. The results showed that cases of CINV in group PA ended more quickly. Group PA also had more days with no vomiting and no nausea than the other two groups. The results of this study propose 6-day aprepitant use as more effective to prevent CINV in patients receiving 3-day cisplatin-based chemotherapy.