The purpose of the present study was to examine whether its is possible to successfully replace ondansetron (OND) with metoclopramide (MCP) in patients exposed to moderately emetogenic chemotherapy who did not experience severe nausea and vomiting while undergoing OND treatment during their first chemotherapy cycle. After switching to MCP, patients continued with this drug for three cycles, provided that they had adequate control of nausea and vomiting. Otherwise, they were switched back to OND. There were 76 patients, 60 women and 16 men, whose median age was 56 (mean 58) years. Karnofsky performance status score was 100 in 18 patients, 90 in 23, and 80 in 11 patients. No patient had previous chemotherapy. Thirty-four patients had breast cancer and received fluorouracil 500 mg/m2, epirubicin 100 500 mg/m2, and cyclophosphamide 500 mg/m2. Twelve patients had small cell lung cancer and received carboplatin 400 mg/m2 + etoposide 120 mg/m2 x 3 days. Twenty patients with ovarian cancer received carboplatin 350 mg/m2 and cyclophosphamide 500 mg/m2. Ten patients had cancer of unknown primary and received carboplatin 400 mg/m2, epirubicin 60 mg/m2, and etoposide 120 mg/m2 x 3 days. The OND schedule consisted of methylprednisolone 40 mg intravenous bolus followed by OND 8 mg in a 15-min infusion before chemotherapy, followed by OND 4 mg orally x 3 on the same and the next 2 days. Patients who did not experience nausea and vomiting with OND continued with an MCP schedule consisting of methylprednisolone 40 mg bolus followed by MCP 2 mg/kg in a 15-min infusion before chemotherapy, followed by MCP (20 mg x 4 on the day of therapy and the next 2 days after). Patients who failed with MCP or OND continued with OND. Considering our results as a whole, the intensity of nausea does not appear to influence the results of Gralla's scale. The results of Gralla's scale do not appear to be affected by the analysis of the antiemetic results and nausea on the next 2 days following chemotherapy administration. Overall, patients received 145 cycles with OND and 159 cycles with MCP. Of the 76 patients receiving OND-based antiemetic regimen during the first cycle, 13 (21%) experienced severe vomiting (Grade 2, 3) and the remaining 63 (79%) had mild or no vomiting (Grade 0, 1). Patients with Grade 0, 1 vomiting (63, 83%) continued with MCP in the second cycle. The final number of patients who failed on MCP, after 4 cycles of chemotherapy increased to 33 (43%); 43 (57%) were able to complete chemotherapy with MCP. Headache occurred in 15 (10%) cycles with OND and 8 (5%) with MCP. Flushing was noted in 12 (8%), and constipation occurred in 43 (30%) of OND cycles, and extrapyramidal manifestations occurred in 3 (5%) of patients receiving MCP. Diarrhea was noted in 3 (2%) of cycles with OND and in 28 (18%) with MCP. The cost ratio between MCP and OND was 1:14. If we administered OND only in patients who needed it, the overall cost decreased to 44%. Following the strategy applied in the present study, the cost decreased to 47%.