This is a multi-center, randomized, non-inferiority phase 3 study conducted to determine an appropriate anti-emetic regimen for patients receiving melphalan for an autologous stem cell transplant (SCT). Candidates for this trial will include patients aged 18-80 years with hematologic malignancies receiving high dose melphalan as part of a conditioning regimen for an autologous stem cell transplant. Patients will be enrolled in 2 arms. Patients in Arm A will receive an aprepitant containing anti-emetic regimen. Patients in Arm B will receive an olanzapine containing anti-emetic regimen. Patients must be able to tolerate oral medications.