Objective :To observe the effects of iiiac crest composite free flap (ICCFF) in the reconstruction of mandibular defects. Methods:Mandibular defects were reconstructed with ICCFF in 5 cases. "Window flap" was used to monitor the blood supply of ICCFF. Follow-up was carried out for 1 year and the effects of reconstructionwere evaluated by general observation and radiography. Results:Satisfactery face contour and bony healing of the grafts with the adjacent bone bed were observed in all the cases. Conclusion: ICCFF can be used to reconstruct large defects in mandible and the "window flap"can be used to moniter the blood supply of bone grafts.