Paget's disease is one of the chronic disorders of skeletal system which is frequently accompained with pathologic fractures. This disease is extremely rare in Korea and only three cases have been reported in the Journal of Korean Orthopaedic Associstion. And all these cases were not associated with pathologic fracture. We experienced a case of Paget's disease with pathologic fracture of the femur which is typical in radiologic, laboratory and histopathologic findings.