Twenty-three women with a diagnosis of breast cancer who subsequently developed new nonmetastatic rheumatic symptoms, and/or had a history of rheumatic symptoms prior to their diagnosis of breast cancer, were identified from the oncology and rheumatology practices of a 400-bed tertiary-care teaching hospital. For each patient a structured telephone interview and detailed chart review were conducted. Of eight women with no previous rheumatic history (Group I), four developed polyarthritis (1 seropositive), three fibromyalgia, and one spondylosis after the diagnosis of breast cancer, which in four cases occurred during or shortly after cyclophosphamide-based combination chemotherapy, in two cases during tamoxifen therapy, and in one case after radiotherapy only. Of 15 women who had previous rheumatic symptoms (Group II), 12 developed worse and/or new symptoms, five after chemotherapy and seven on tamoxifen. In both groups the symptoms had a significant negative impact on functional status, and in some cases resolution was only partial even after many years of followup. Prospective studies are needed to determine the incidence, risk factors, and optimal management of nondestructive polyarthropathy or fibromyalgia in women who receive systemic adjuvant therapy for breast cancer.