Chemotherapy-related nausea and vomiting can be controlled with available antiemetics in a high percentage of patients, while emesis remains a critical problem in some subgroups and with certain drugs. In the ceaseless attempt to find newer drugs and better treatment modalities, a sound methodology in antiemetic research is essential. Several factors should always be considered when planning an antiemetic trial: first, the different emetic power of various chemotherapy agents, their dosages and route and schedule of administration and second, the type of antiemetic used, its dosage and timing, and its possible combination with other antiemetics. Important factors which influence outcome but which are often under-evaluated are those related to patient population such as age, gender, and previous experience with chemotherapy. Considering the relevance of subjective phenomena in nausea and vomiting, it is essential that any study be randomized and double blinded. The parallel type of study design is preferable to the cross-over and a large number of patients is usually required to achieve meaningful results. Efficacy and toxicity should be properly evaluated by trained personnel in a standardized way, using a validated, relatively simple methodology.