BACKGROUND: The induced-membrane technique was initially described by Masquelet as an effective treatment for large bone defects, especially those caused by infection. Here, we report a case of chronic osteomyelitis of the radius associated with a 9 cm bone defect, which was filled with a large allogeneic cortical bone graft from a bone bank. Complete bony union was achieved after 14 months of follow-up. Previous studies have used autogenous bone as the primary bone source for the Masquelet technique; in our case, the exclusive use of allografts is as successful as the use of autologous bone grafts. With the advent of bone banks, it is possible to obtain an unlimited amount of allograft, and the Masquelet technique may be further improved based on this new way of bone grafting. CASE SUMMARY: In this study, we reported a case of repair of a long bone defect in a 40-year-old male patient, which was characterized by the utilization of allograft cortical bone combined with the Masquelet technique for the treatment of the patient's long bone defect in the forearm. The patient's results of functional recovery of the forearm were surprising, which further deepens the scope of application of Masquelet technique and helps to strengthen the efficacy of Masquelet technique in the treatment of long bones indeed. CONCLUSION: Allograft cortical bone combined with the Masquelet technique provides a new method of treatment to large bone defect.