In a prospective, randomized study, an individual psychosocial support intervention performed by specially trained oncology nurses, or psychologists, were compared with standard care. Consecutive primary breast cancer patients about to start adjuvant therapy (n = 179) were included. Data were supplied by the questionnaires European Organisation for Research and Treatment of Cancer Quality of Life Study Group Core Quality of life questionnaire with 30 questions (EORTC QLQ-C30) and Breast Cancer Module with 23 questions (BR23), the Hospital Anxiety and Depression Scale, Spielberger's State-Trait Anxiety Inventory, and the Impact of Event Scale before randomization and 1, 3, and 6 months later. Patient files provided data on utilization of psychosocial support offered in routine care. Global quality of life/health status, nausea and vomiting, and systemic therapy side effects were the subscales showing significant Group by Time interactions, favoring the interventions. Intervention groups improved statistically significantly more than the standard care group regarding insomnia, dyspnea, and financial difficulties. Nurse patients experienced less intrusion compared with the standard care group. All groups showed statistically and clinically significant improvements with time on several subscales. The intervention groups, however, improved to a greater extent. Fewer patients in the intervention groups used psychosocial hospital support compared with the standard care group. In conclusion, psychosocial support by specially trained nurses using techniques derived from cognitive behavioral therapy is beneficial for breast cancer patients and may be a realistic alternative in routine cancer care.