Better tolerated and more effective means of controlling chemotherapy-induced nausea and vomiting have been introduced over the past decade. Despite the progress made, incompletely controlled emesis is a persistent problem for significant numbers of patients receiving chemotherapy. Efforts to improve antiemetic control further are ongoing. The most interesting new class of antiemetics under development focuses on antagonism of the neurotransmitter substance P. Substance P exerts its effects by binding to the tachykinin neurokinin NK1 receptor. A number of selective antagonists of the NK1 receptor have been synthesized and, when used in preclinical models, have demonstrated an ability to antagonize the emetic effects of a number of stimuli, including chemotherapy agents such as cisplatin. Over the past 3 years, results of the initial studies evaluating this class of agents for cisplatin-induced emesis in cancer patients have begun to appear. These agents have been well tolerated. As single agents, they appear to be no more effective than 5-HT3 receptor antagonists in preventing acute cisplatin-induced emesis. Their real value may be found in combination with existing agents and in the treatment of delayed emesis. The results of ongoing clinical trials will hopefully define the utility and appropriate place for this new class of agents in the management of chemotherapy-induced nausea and vomiting.