Abstract: Objective 　To investigate the inhibiting ability of Ibandronate on a skeletal metastasis model of lung caner. Methods 　A skeletal metastasis model of lung caner was established by injection of small cell lung carcinoma line (SCLC) H446 cells into the right leg of nude mice proximally to the tibia, and Ibandronate (5μg/ animal/ day) was given subcutaneously ( s. c. ) to the animals af ter radiologically small but defined osteolytic metastases were observed. Both X-ray and histological assay were applied to evaluate effects of Ibandronate. Results 　Both X-ray detection and 99 Tcm-MDP imaging demonst rated that implant of H446 caused the development of bone lesions. Histological studies showed abnormal reacting bone formation preceded by tumor metastasizing and a number of cancer cells invading into bone marrow. But in the treated group, Ibandronate not only markedly suppressed the progression of established bone metastases lesions in nude mice, but also prevented the development of lung cancer cells in bone marrow. The reacting bone formation was limited locally. Conclusion 　These results suggest that Ibandronate may be a choice for the treatment of metastasis cancer in bone.