The effects of the mouth care using cool normal saline on oral discomfort were investigated in 40 patients on chemotherapy. The subjects were divided into two groups, one was experimental group(N=20) in which the subjects were provided mouth care with cool normal saline, the other was the control group(N=20). The data was collected from June. 20 to Oct. 30 in 1998. Oral discomfort was measured by Self Reported Oral Discomfort Assessment Instrument developed by Jung(1995) and Oral Assessment Guide (OAG) Instrument developed by UNMC. Collected data were analyzed by means of frequency, percentage, standard deviation, chi-squre test, t-test. The results were summarized as follows: 1. 'The experimental group which recieved oral care with cool normal saline shoud be lower self reported oral discomfort on 3, 5, 7, 14 days after chemotherapy was supported (p=.025-.000). 2. 'The experimental group which recieved oral care with cool normal saline shoud be lower observational symptom oral discomfort on 3, 5 days after chemotherapy was not supported, but on 7, 14 days after chemotherapy was supported(p=.0011, 0.001). In conclusion, the patient who recieved oral care with cool normal saline showed the decrease in degree of oral discomfort of cancer patient undergoing chemotherapy. So oral care with cool normal saline had been judged the nursing intervention to improve oral discomfort of cancer patients undergoing chemotherapy.