RESEARCH OBJECTIVES: To assess the coping styles used by breast cancer patients in response to stressful situations. To evaluate the subjective well - being experienced by breast cancer patients. To investigate the relationship between coping styles in stressful situations and subjective well - being (life satisfaction, positive and negative experiences and prosperity) in breast cancer patients. STUDY DESIGN: Cross - sectional study. PARTICIPANTS AND METHODS: The research was conducted at the Department of Oncology, Clinical Hospital Center Osijek, and the participants were adult breast cancer patients treated in May and June 2023. A total of 56 patients were included. The data collection methods included the use of a validated questionnaire - The Brief Coping Orientation to Problems Experienced (Brief - COPE) and Dienerˈs three scales of subjective well - being (Diener, 2009.). The Brief - COPE questionnaire consists of 28 self - assessment items designed to measure effective and ineffective ways of coping with stressful life events. Dienerˈs three scales include the life satisfaction scale, positive and negative experience scale and prosperity scale. The Satisfaction with Life Scale (SWLS) is a short 5 - item questionnaire designed to measure individuals life satisfaction judgments. The Positive and Negative Experience Scale (SPANE) is a short 12 - item scale in which participants are asked to rate how often they experience different states. The Prosperity Scale uses a Likert scale ranging from 1 (strongly disagree) to 7 (strongly agree). The total scores range from 8 to 56, with higher scores indicating positive self - perception in important areas of functioning. RESULTS: A problem-oriented coping style dominates in patients with breast cancer. A high expression of feelings of well-being and life satisfaction was observed, as well as a higher prevalence of positive than negative feelings according to the patients' self-assessment. There is a positive relationship between coping with a problem and life satisfaction, while avoiding coping is related to negative feelings. CONCLUSION: Coping style is a significant factor in the subjective well-being of breast cancer patients. Coping with a problem is positively related to higher life satisfaction, while avoiding coping is related to negative feelings.