To describe and compare changes in quality of life in two groups of patients with breast cancer and to identify factors predicting negative changes in quality of life within six months. Women with breast cancer suffer from various treatment side-effects, from psychological and social symptoms as well as decreased quality of life, creating a need for support that may persist throughout the breast cancer experience. This six-month longitudinal study involved a sample of 164 women, who were quasi-randomized between intervention ( n = 85) and control groups ( n = 79) after breast cancer surgery. Intervention group received support and education via telephone one week after the breast cancer surgery and face-to-face support six months after the surgery. Quality of life was estimated one week and six months after breast cancer surgery, using the Quality of Life Index - Cancer Version (QLI-CV) and the European Organisation for Research and Treatment of Cancer Breast Cancer - Specific Quality of Life questionnaire (EORTC QLQ-BR23). Data were analysed statistically using descriptive statistics and non-parametric tests. Factors predicting negative changes in quality of life within six months were investigated using logistic regression models with the enter method. Significant group difference in the magnitude of changes within six months was found in future outlook. Logistic regression analyses revealed six significant predictors of negative changes in quality of life within six months: education, employment status, having underaged children, chemotherapy, radiotherapy and hormonal therapy. The results of this study underline the importance of identifying quality of life changes in patients with breast cancer and paying attention to those women with difficulties in adapting to being a cancer survivor. The findings of this study provide evidence which may help to create appropriate supportive interventions for both acute and long-term settings.