Abstract: Objective: To explore the influencing factors for bone metastasis of breast cancer.Methods: The clinical data of 136 breast cancer patients with bone metastasis treated in the First Af-filiated Hospital of Chongqing University of Medical Sciences, from January, 1990 to April, 2005, wereanalyzed retrospectively.Results: ①All the cases were confirmed with X- ray, CT, MRI, or ECT andmost of them (2/3) were diagnosed with two or more the above methods; ②Since diagnosis of bonemetastasis, the breast patients had been followed for 2 months to 15 years and 5 months (with the meanvalue of 27.2 months); ③The occurrence rate of bone metastasis was 9. 9% and the mean occurrenceduration were 34.0 months after operation; ④The occurrence of bone metastasis was positively relatedwith high clinic staging, poor pathological type, axillary lymph node metastasis and long following- upduration; ⑤29.4% cases of bone metastasis were axillary lymph node- negative, with chronic durationand certain features ⑥the death rate of bone metastasis accompanied with other visceral or soft tissuemetastasis was 80.4% (45/56), while that of simple bone metastasis was 20.0% (16/77) (χ² =45.38, P<0.001). Conclusions: The main influencing factors for osseous metastasis of breast cancer are clinicalstaging, pathological type, axillary lymph node metastasis and follow-up duration. Certain ratios ofbreast cancer patients with negative axillary lymph node metastasis, suffered from osseous metastasis,suggest that systemic treatment, such as chemotherapy, takes an important role in prevention and treat-ment on the osseous metastasis of breast cancer.