Stable and unstable internal fixation of fractures was performed in rabbits. After inoculation with Staphylococcus aureus, clinically manifest osteitis occurred only in the very unstable fractures. Abscesses, sinuses and sequestra developed in 45 per cent of the unstable fractures, whereas clinically manifest osteitis did not occur after rigid fixation. With rigid fixation there was no significant difference in the time to bony union between the infected and uninfected fractures. It seems that the development of osteitis and the healing of a fracture are both related to the degree of rigidity, but remain independent of each other. The significance of these findings in the management of posttraumatic osteitis is discussed.