Objective To discuss the midterm results of modular femoral prosthesis in total hip revision surgery for bone defects.Methods From December 2001 to June 2006,by using Link-MP modular femoral prosthesis for muhiple reasons(48 with asepsis loosening,seven with infections using two-stage revision procedure,one with fracture of proximal femur and one with periprosthetie fracture), total hip revision surgery was carried out in 56 eases including 24 males and 32 females with age range of 38-77 years(mean age 58.8years).Causes for revision included sterile prothesis loosening in 48 cases, infection of hip prosthesis in seven and peripheral fracture of femoral stem fracture prosthesis in one.Re- vision for infected femur was all at stageⅡ.Of 56 cases with femoral stem prosthesis loosening,30 had loosening of primary cemented prosthesis and 26 of uncemented prosthesis.According to the Mallory bone defect classification,five eases were with typeⅡbone defect,21 with typeⅢA,28 with typeⅢB and two with typeⅢC.Bone grafting was performed in 12 cases and wire or cable cerelage in 28.Fracture of great trochanter was found in two cases,fracture of femoral stem in three and perforation of femoral stem in one.Results A total of 52 eases half year after operation were followed up for mean 31.78 months (8-56 months).No migration of distal femoral stem was found in all eases except for one ease had 1.5 cm subsidence of proximal femoral stem.The Harris hip score was preoperative 46 scores(21-52)and post- operative 89(79-94).There found no significant limb discrepancy,thigh pain or dislocation.Conclu- sions Total hip revision surgery for femoral bone defect using modular femoral prosthesis has optimal midterm result especially in its advantages of regulating limb length,offset,anteversion,which can help us match the proximal femur with distal femur and achieve initial and long-term stability.