Between May, 1984 and October, 1986, twenty patients were treated at Han-Ra Hospital of JejuCity and Chung-Ang University Hospital of Seoul with immediate internal fixation with or without bone graft of open fractures of the long bones within three days. Fractured bones were ten tibiae, six femurs, three humeri and one radius and ulna. The injuries were classified on the basis of extent of soft tissue injury as defined by Gustilo and Anderson and consisted of four TypeI injuries, five Type II injuries and eleven Type III injuries. All wounds were closed primarily and radiological follow up was qhecked every month till union occurred. The complications included two deep infections, one non-union and one amputation. This study demonstrates that immediate internal fixation with bone graft when necessary is a beneficial method of treatment of open fractures of the long bones if copious irrigation, adequate debridement and skillful internal fixation technique are given golden period after injury. The results were related to the severity of the initial soft tissue injury and surgical technique and the period of union was not related to the individual bone. Autogenous bone grafting at the time of immediate internal fixation in comminuted or segmental fractures in which interfragmental compression cannot be obtained is recommended.