Autologous stem cell transplant (ASCT) requires therapy with very highly emetogenic chemotherapy regimens. Nausea and emesis are a major issue for patients undergoing ASCT. Aprepitant, a selective substance-P/neurokinin 1 (NK1) receptor antagonist, has been approved by the U.S. Food and Drug Administration for treatment of acute and delayed CINV in combination with a corticosteroid and 5-HT3 receptor antagonist. Due to little patient data in this area, a retrospective chart review was performed which evaluated 41 ASCT patients that had received standard therapy (control group, n=25) compared to aprepitant in addition to standard therapy (aprepitant group, n=16). Patients who underwent an ASCT and were greater than 18 years of age were eligible for inclusion in the study. Patients who underwent an allogeneic stem cell transplant were excluded. All data was collected from the hospital’s computerized nurse charting system. Episodes of nausea and emesis were collected from nursing notes while data for rescue medications was collected from the charted medications. Conditioning regimens given during the study included high dose (HD) melphalan, BEAM (carmustine, etoposide, cytarabine, and melphalan) or R-BEAM (rituximab, carmustine, etoposide, cytarabine, and melphalan). All patients evaluated in the aprepitant group had received aprepitant 125 mg orally once daily on the first day of chemotherapy administration and 80 mg orally once daily the following 2 days in the HD melphalan group (Day -1 through Day 0) and the following 5 days in the BEAM group (Day-6 through Day -1). Although aprepitant dosing was consistent, dosing was determined by the individual physician and prescribed on a patient-specific basis. The primary endpoint was the number of episodes of nausea and emesis after chemotherapy, while the secondary endpoint was the number of rescue medications that were used for nausea and emesis. For the primary endpoint of the study, the mean number of nausea episodes per patient was reduced in the aprepitant group compared to the control group in the acute phase (1.7 versus 2.2, p=0.51) and delayed phase (5.3 versus 5.6, p=0.83). Emetic episodes per patient were decreased in the aprepitant group compared to the control group in both the acute (0.06 versus 0.9, p=0.21) and delayed phases (0.9 versus 2.4, p=0.17). Use of rescue medication per patient was decreased in the aprepitant group compared to the control group in the acute phase (2.3 versus 3.6, p=0.40) but not in the delayed phases (8.1 versus 8.1, p=0.99). None of the results of this study were statistically significant, although the reduced number of emetic episodes with aprepitant may be clinically significant. The results of this study warrant consideration for a prospective evaluation of this therapy in ASCT patients to greater clarify the use of aprepitant in these patients.