The effects of the mouth care using cool sterile normal saline on oral stomatitis were investigated in 59 patients on chemotherapy. The subjects were divided into two groups, one was experimental group(N=31) in which the subjects were provided mouth care 4 times a day (after meals, before bedtime)with cool normal saline, the other was the control group(N=28), The Oral Assessment Guide(OAG) which it includes eight items(voice, swallowing, lips, tongue, salivation, oral mucous membrane, gingiva & teeth) was used to assess oral status six times(once in the Prechernotherapy Period, and on the third, 5th, 7th, 10th & 14th day postchemotherapy). The means of the total scores at each time were analyzed by repeated ANOVA The results are as follows : 1. The incidence of stomatitis was higher in the control group than in experimental group. The incidence of third grade stomatitis characterized by bleeding, sore, infection & severe pain was 3.3% in the experimental group, and while 21.4% in the control group(p=0.01). 2. The number of stomatitis sites which were occurred in the experimental group were significantly lower than in the control group(p=0.046). 3. The grade of stomatitis(mean of total score) for patients in the control group was significantly higher than for patients in the experimental group (p=0.005). 4. In the control group, voice change increased in the period between the seventh and tenth day after chemotherapy (p=0.04). 5. In the control group, swallowing difficulty was mest severe in the period between seventh and tenth day(p=0.05), and decreased by the fourteenth day(p=0.01). 6. Changes in the lips gradually increased after chemotherapy in the control group(p=0.0025), while they were significantly lower in the experimental group(p=0.0002). 7. The increment of tongue changes started on the third day after chemotherapy reached a peak on the tenth day and decreased by the fourteenth day in both groups(p=0.0016). 8. Driness of the mouth reached a peak on the seventh day after chemotherapy in the control group (p=0.05). 9. The degree of oral mucositis was significantly higher in the control group than in the experimental group(p=0.02) . In the control group, the mucosal change started three days after chemotherapy and reached a peak on the tenth day(p=0.03). 10. Changes in the gingia were significantly higher in the control group(p=0.03). In control group, the degree of gingivitis reached a peak on the tenth day. In conclusion, meuth care with normal saline four times a day could reduce the incidence and grade of stomatitis. Stomatitis was shown to begin on the third day after chemetherapy, reach a peak on the tenth day and be reduced by fourteenth day.