Abstract: OBJECTIVE To observe the clinical effect of nystatin combined with sodium bicarbonate on prevention of oral infections in tumor patients after radiotherapy so as to seek the most appropriate treatment method for the patients with oral infections. METHODS A total of 300 tumor patients with oral infections who received the radiotherapy in the hospital from Jan 2013 to Feb 2014 were enrolled in the study and randomly divided into the experimental group and the control group, with 150 cases in each group. The control group was treated with normal saline, mouth Thai gargles for oral gargle, while the experimental group was given nystatin combined with sodium bicarbonate for mouth gargle. The incidence rates of oral infections and complications were investigated, the curative effects were observed, and the statistical analysis was performed with the use of SPSS 15.0 software. RESULTS The incidence rate of bad breath was 6.00% in the control group, 1.33% in the experimental group; the incidence rate of sore gums was 6.67% in the control group, 2.00% in the experimental group; the incidence rate of oral ulcers was 14.00% in the control group, 2.00% in the experimental group; the incidence rate of oral plaque was 10.67% in the control group, 2.67% in the experimental group; as compared with the two sets of data, there was significant difference (P<0.05). The oral pH value was 4.8±0.3 in the experimental group after the related treatment, 7.5±0.6 in the control group, and there was significant difference between the two sets of data (P<0.05). CONCLUSION Nystatin combined with sodium bicarbonate can achieve significant effect on prevention of oral infections in the tumor patients after the radiotherapy, remarkably reduce the incidence of oral infections and bad breath as well as oral ulcers, and effectively improve the oral pH value.