OBJECTIVE The study assessed and compared the psychosocial needs of patients with breast cancer and of their relatives, the patients' and relatives' burden of illness, anxiety, depression and distress and assessed the patients' cancer treatment-related symptoms and identified relevant factors influencing patients' and relatives' needs. METHODS Seventy-two patients (n=72) participated with a relative in a cross-sectional mail-survey, 1-22 months after cancer treatment. RESULTS The patients reported needing help with psychological and sexual issues. They suffered from treatment-related symptoms. More treatment-related symptoms and depression were related to the patients' needs for supportive care. Their relatives' needs primarily concerned access to information and communication with health care professionals. Relatives had higher levels of anxiety (25.0% vs. 22.2%), depression (12.5% vs. 8.3%) and distress (40% vs. 34%) than patients. Higher levels of depression, younger age and having a disease themselves were associated with relatives' need for help. CONCLUSIONS Patients' and relatives' substantial needs and psychological problems require professional support even after completion of the patients' treatment. Continued assessment of the patients' and their relatives' needs and of the patients' symptoms provide the basis for purposeful counselling and education. Rehabilitation programs for patients and their relatives should be developed and implemented in clinical practice.