The present study investigated the changes of quality of life, mood, and the tumor marker CA 15-3 associated with a 3-week inpatient breast cancer rehabilitation program incorporating spa therapy. One hundred forty-nine women, 32 to 82 years, participated in the study 3 to 72 months after breast cancer surgery. Quality of life (QoL, EORTC QLQ-C30), anxiety, and depression (HADS) were measured 2 weeks before, at the end, and 6 months after rehabilitation; CA 15-3 at the beginning, end, and at 6 months follow-up. Patients received an individualized rehabilitation program incorporating manual lymph drainage, exercise therapy, massages, psychological counseling, relaxation training, carbon dioxide baths, and mud packs. Quality of life and mood improved significantly, the greatest short-term improvements found for mood-related aspects of quality of life, the most lasting improvements found for physical complaints (eg, fatigue). Also, the tumor marker CA 15-3 declined significantly to follow-up. Patient characteristics, as well as the time since surgery, moderated rehabilitation outcome to a limited extent. Older patients, nonobese patients, patients with a greater lymphedema, and patients with an active coping style showed slightly greater improvements. Hot mud packs inducing hyperthermia did not affect CA 15-3. In conclusion, the combination of inpatient rehabilitation with spa therapy provides a promising approach for breast cancer rehabilitation.