Objective To observe the effect of fresh orange peel flavor inhalation on the improvement of gastrointestinal reactions such as nausea and vomiting in tumor patients during chemotherapy. Methods Ninety-one inpatients undergoing chemotherapy with PF and TP regimens between May 2012 and September 2013 were included in this study. The patients were randomly divided into orange group (n=45) and control group (n=46). Patients in the control group received conventional care, while those in the orange group were treated with fresh orange peel flavor inhalation during chemotherapy. We observed the effect of orange peel flavor inhalation on such gastrointestinal reactions as nausea and vomiting in tumor patients during chemotherapy. Results All the patients completed each cycle of chemotherapy. At the fifth day during chemotherapy, compared with the control group, the incidence rates of grade Ⅲ-Ⅳ gastrointestinal reactions (nausea and vomiting) in the orange group were significantly lower (P=0.023). At the fourth day, when gastrointestinal reactions were the most significant, the food intake of patients in the orange group was significantly higher than that in the control group (P=0.012). During chemotherapy, the addition rate of antiemetic drugs in the orange group was significantly lower than that in the control group (P=0.038). In the orange group, 80.0% of the patients had good self-feeling after orange peel flavor inhalation. Conclusions The study results have shown that fresh orange peel flavor inhalation can effectively improve the gastrointestinal reactions (such as nausea and vomiting), appetite, and degree of comfort in tumor patients during chemotherapy, and reduce the use of antiemetic drugs. This study is of great significance to guide the future research on how to reduce the discomfort of on-chemotherapy patients and provide more comfortable care.