Chemotherapy-induced nausea and vomiting (CINV) is a serious complication of treatments of hematological malignancies. Although aprepitant, an NK1 receptor antagonist, has been shown to control CINV in highly emetogenic therapies for solid tumors, the antiemetic effect of this agent in hematological chemotherapies is not well established. In this randomized controlled trial, we examined the additional effect of aprepitant in combination with conventional 5HT3 blocker-based prophylaxis for CINV in highly or moderately emetic chemotherapies for hematological malignancies (n = 41). The complete response rate, defined as no emetic episodes and no salvage treatments, was significantly higher in the aprepitant arm than the control arm (82 versus 47 %, p = 0.026), with no increase in severe adverse effects. However, the difference of nausea, measured with visual analog scale, and of oral intake impairment was moderate, which suggests insufficiency of blocking NK receptor for these events. Furthermore, sub-group analysis revealed that merit of aprepitant addition depends on treatment regimens. Our results indicate the overall advantage of applying aprepitant in the control of CINV in hematological malignancies and the need for further refinement of anti-CINV strategies, including stratification according to regimen.