1. In a series of 129 tibial fractures treated by compression plates, a high incidence of complications causing delay in healing was found in alcoholics and persons with abnormal personality traits. 2. The healing time and time off work for these people were about doubled. 3. The indications for internal fixation in such patients should therefore be sharply defined and, if used, added protection should be given by institutional care and by well controlled plaster casts.