Fifty-three high-energy tibial fractures treated with early prophylactic posterolateral bone grafting were retrospectively reviewed. The bone-grafting procedures were performed at a mean of ten weeks following injury and at a mean of eight weeks following soft-tissue coverage. Ninety-six percent of the fractures had associated injuries with a mean injury severity score of 20.9. Seventy-nine percent of the fractures were classified as Grade III open fractures, and 40% had bone loss greater than 50% of the cortical circumference. Ninety-six percent of the fractures healed at a mean time of 43 weeks after injury. Segmental bone loss and soft-tissue injury requiring flap coverage were the best predictors of prolonged time to union. Comparison with a matched historical control group of tibial fractures not receiving early bone grafts revealed a mean reduction in time to union of 11.7 weeks (p = 0.03). The incidence of chronic osteomyelitis was 1.9%. These results are attributed to early and repeated aggressive debridement, immediate rigid external fixation, early soft-tissue coverage, and early posterolateral bone grafting. Recommendations include posterolateral cancellous bone grafting two weeks following wound closure by delayed primary closure, split-thickness skin graft, or local rotational myoplasty. A six-week delay following freely vascularized soft-tissue coverage prior to bone grafting is suggested.