Two hundred and sixty-nine patients with breast cancer were assessed with regard to multiple parameters at the time of initial diagnosis. Over a follow-up period of 6 or 7 years, 84 patients developed skeletal metastases and in 42 they were symptomatic. Symptomatic bone metastases were related to lytic metastases and an elevated sedimentation rate. The significant parameters predisposing to the development of bone metastases were the presence of adenopathies or metastases at the time of initial diagnosis. The number of axillary nodes involved was related to the number of bone metastases, the number of spontaneous abortions, and the gonadal endocrine function. The adherence of axillary nodes was related to the number of bone metastases, an elevated sedimentation rate and the serum calcium level.