The purpose of this study is to determine the control of acute and delayed chemotherapy-induced nausea and vomiting (CINV) in patients receiving moderately emetogenic chemotherapy (MEC) and highly emetogenic chemotherapy (HEC) with the combined use of palonosetron and olanzapine, and dexamethasone with the dexamethasone given on day 1 only. Forty chemotherapy-naive patients received on the day of chemotherapy, day 1, an anti-emetic regimen consisting of dexamethasone, palonosetron, and olanzapine. Patients continued olanzapine for days 2-4 after chemotherapy administration. Patients recorded daily episodes of emesis, daily symptoms utilizing the M.D. Anderson Symptom Inventory, and the utilization of rescue therapy. For the first cycle of chemotherapy, the complete response (no emesis, no rescue) for the acute period (24 h post-chemotherapy) was 100%, the delayed period (days 2-5 post-chemotherapy) 75%, and the overall period (0 120 h post-chemotherapy) 75% in 8 patients receiving HEC and was 97, 75, and 72% in 32 patients receiving MEC. Patients with no nausea for the acute period was 100%, the delayed period 50%, and the overall period 50% in 8 patients receiving HEC and was 100, 78, and 78% in 32 patients receiving MEC. The complete response and control of nausea in subsequent cycles of chemotherapy were not significantly different from cycle one. Olanzapine combined with a single dose of dexamethasone and a single dose of palonosetron was very effective in controlling acute and delayed CINV in patients receiving both HEC and MEC.