The medical records of 414 patients with metastatic breast carcinoma treated between 1978 and 1986 were reviewed and 44 women were identified as having stage IV disease when the primary breast lesion was detected. Of these 44 women, 25 had metastatic disease limited to the skeleton while 19 had extraosseous lesions only. The clinical features, response to therapy, and survival were analyzed and compared for both groups. The median survival of those patients with bone-only metastases was 52 months as compared with 13 months for those with extraskeletal lesions (p = 0.0025). The response rate to first-line systemic therapy was similar for both groups (47% for bone metastases and 44% for extraosseous metastases). The median duration of response was 14 months (range, 3-55 months) for patients with bone disease and 8 months (range, 4-43 months) for those with extraskeletal lesions. We conclude that patients with metastatic breast cancer confined to the skeleton at initial diagnosis tend to follow an indolent, chronic course with prolonged survival. Therefore the increase in response rate with aggressive chemotherapy should be balanced against its higher morbidity. Further studies are needed to confirm whether the better prognosis of these patients is determined by the anatomical confinement of the disease to the skeleton or merely reflects the influence of other prognostic factors.