To evaluate whether the incidence of emesis in patients undergoing cisplatin chemotherapy and receiving the standard antiemetic prophylaxis during daily clinical practice was similar to that obtained in antiemetic trials, a prospective study was carried out, adopting very wide eligibility criteria. In the first cycle of chemotherapy, 308 consecutive adult patients were evaluated, 112 in the second, and 89 in the third cycle. Results were compared with those obtained in three published randomized clinical trials. In the first cycle of chemotherapy, complete protection from acute vomiting/nausea was obtained by 78.9% (243/308) and 71.8% (221/308) of patients. These results were quite similar to those obtained in the three randomized studies: 79.7%/72.1%, 78.3%/71.4%, and 78.7%/77.2%. No significantly different results among these studies were obtained, even in the second and third cycles of chemotherapy. In conclusion, in patients undergoing cisplatin chemotherapy, the effectiveness of the same standard antiemetic prophylaxis is similar to the efficacy found in randomized clinical trials, regardless of the eligibility/exclusion criteria and the setting of the study.