Fosaprepitant is administered intravenously to treat chemotherapy-induced nausea and vomiting. To verify the incidence of infusion site reactions and the relationship among risk factors, a quantitative retrospective cohort study was undertaken. The study included patients seen between October 2013 and February 2014. Fifty-seven patients were included in the study, and there were 105 infusions among them. Infusion site reactions were identified in 42 (40%) cases. Risk factors identified by the study included age (P < .001), insertion at the back of the hand and wrist (P < .001), and first fosaprepitant administration (P < .001). The study found evidence of a higher incidence of infusion site reactions than was reported in the package insert.