Recent developments in chemotherapeutic regimens have improved overall and progression-free survival in patients with various malignancies. Supportive care accompanied by antiemetic treatment is crucial for successful chemotherapy. Hence, high-level evidence with regard to antiemetic therapy is essential to create awareness among oncologists. This study reviewed evidence from clinical trials involving antiemetic therapy in Japanese patients with malignancies, and established an antiemetic guideline for oncologists in Japan. Here, we introduce the outline of this antiemetic guideline.