to review the topic of prognostic factors for chemotherapy-induced nausea and vomiting. Multiple patient factors such as age, gender and alcohol intake have been found that affect the likelihood of emesis with a given chemotherapy. Pharmacogenomics has also been explored as a cause for variation in emetic response. In theory these risk factors could be used to optimize antiemetic therapy for individual patients but guidelines for prophylactic antiemetics are based solely upon the type of chemotherapy administered. Attempts to identify subgroups of patients for whom guidelines recommendations are suboptimal have thus far been unsuccessful except for those with a poor experience in a previous cycle of the same chemotherapy. At present, there is no basis for deviating from evidence-based guidelines when prescribing antiemetics prior to the first cycle of chemotherapy.