Chemotherapy-induced nausea and vomiting is a major debilitating side effect of oncology treatment despite recent advances in pharmaceutical management. Nurses who provide care to patients experiencing nausea and vomiting are often only marginally aware of the pathophysiological processes involved in the treatment. A better understanding of the science behind current interventions to reduce nausea and vomiting may help nurses use those interventions more effectively. This article reviews current knowledge about the pathophysiology of chemotherapy-induced nausea and vomiting. By understanding the pathophysiology behind this patient experience, gastroenterology nurses can develop a better understanding of the common symptoms of nausea and vomiting in general. When a nurse understands the complexity of factors causing nausea and vomiting, he or she will be better able to provide appropriate interventions to reduce these symptoms.