Complication rates were compared in 140 smoking and 133 non-smoking patients with open tibial fractures. Both the groups were evenly matched demographically and in terms of primary fracture treatment. Flap failure complicated 7 (20%) patients in the smoking group and 4 (14%) in the non-smoking group. The mean time to union was 32 weeks for smokers and 28 weeks for non-smokers (P<0.05). Bone grafting to stimulate union was required in 36 (26%) smoking patients compared with 24 (18%) non-smoking patients. In patients treated by intramedullary nailing exchange, nailing to achieve union was carried out in 24 (38%) smoking cases compared with 13 (26%) of non-smoking cases. Smoking is associated with an increased risk of complications in patients with open tibial fractures. There is an increased rate of flap failure, delayed union and non-union. We recommend patients with open tibial fractures should be advised to stop smoking to minimise these complications.