Purpose: The aim of this study was to identify the effects of auricular acupressure on nausea, vomiting and serum serotonin level in gynecological cancer patients with chemotherapy. Methods: The research was a randomized control group pretest-posttest design. Participants were 26 patients for the experimental group, and 26 patients for the control group. Auricular acupressure in Shen men, Occiput, Stomach and Sympathetic points was administered to those in the experimental group. Data were analyzed using ${chi}^2$-test, t-test, ANCOVA, and repeated measures of ANOVA. Results: The experimental group had reported significantly lower mean nausea NRS (Number Rating Scale), INVR (Index of Nausea, Vomiting, and Retching), and serum serotonin level than those in the control group. Conclusion: Results of the study show auricular acupressure is an effective nursing intervention for reducing chemotherapy-induced nausea, vomiting and serum serotonin level of gynecological cancer patients.