The purpose of this study was to provide basic information for developing a nursing intervention that helps patients learn how to acquire coping to reduce post operation uncertainty and anxiety by investigating the level of uncertainty and anxiety experienced by mastectomy patients. The subjects were 134 patients selected from St. Mary's Kangnam and St. Mary's hospital, and the data collection period was from October to December of 1998. Uncertainty was measured by using Mishel Uncertainty in Illness Scale (MUIS), anxiety measured by using State-Trait Anxiety Inventory(STAI), and coping by using a questionnaire developed by Kim & Yoo (1996). Data were analyzed with SAS program by t-test, ANOVA, Duncan's multiple range test, Pearson correlation coefficients, and stepwise multiple regression. The results were as follows: 1. The mean uncertainty score was 57.6. The results of the correlation between the compliance of medical regimen and demographic characteristics were as follows ; Those who monthly income over 2,010,000 won had lower than above 1,000,000 won, and those with the experience of chemotherapy had higher than those without, and the patient who has 7~12 months(1 yr.) post operation period had higher than the one below 6months, 25~36 months(3 yrs.), 37~60 months(5 yrs.), and over 61 months. 2. The mean anxiety score was 45.9. Anxiety tended to be increased slightly in subjects with low educational background, poor monthly income, experience of chemotherapy, and 7~12 months(1 yr.) post operation period, but there was no significant difference by general characteristics. 3. The mean value of the coping score was 100.7. The study revealed higher score in problem-focused coping than emotion-focused coping. In regard to coping by demographic characteristics were as follows ; those who had monthly income over 2,010,000 won had higher level of coping than those whose monthly income was between 1,010,000 and 2,000,000 won. In terms of problem- focused coping, those who had 25~36 months of post operation period showed significantly lower level of coping than those below 6 months or 37~60 months(5 yrs.) or over 61 months of post operation period. Regarding the emotion-focused coping, those with the christianity had significantly lower level of coping than those without it. Also, those whose monthly income over 2,010,000 won had significantly higher coping level than those with income of between 1,010,000 and 2,000,000 won. 4. A positive relationship was found between uncertainty and anxiety. Patients who experienced more uncertainty also showed more anxiety. Problem-focused coping was inversely related to uncertainty and anxiety. 5. The major variable that affected uncertainty was anxiety, explaining 63.3% of the uncertainty. In addition to this, it would explain 66.4% in total when experience of chemotherapy was added.