Healing rates of various types of tibial-shaft fractures are compared as to type of treatment. Conservative management in adults is found to have certain advantages and certain limitations. In the case of closed tibial-shaft fractures, no advantage is shown for either open operative or closed treatment. The hazard of introducing infection is considered to be the single greatest deterrent to operative fixation of closed fractures. In this series, primary internal fixation of an open fracture is associated with a very real hazard of infection and with prolongation of the healing rate. Internal fixation of open tibial-shaft fractures should be reserved for those cases with minimal contamination and cases in which stability can be achieved with the least exposure of bone and the least quantity of metal implanted in the limb.