The results after treatment of 50 open and comminuted tibial fractures with Hoffmann's external fixation were analysed. Half of the fractures were treated with bilateral Hoffmann frames, the other half with the Vidal-Adrey double frame modification. The groups were found to be comparable. The results of the study confirm that Hoffmann's external fixation is a safe method for treating the bone and soft tissue lesions in such fractures. There was only one case of osteomyelitis, no definite pseudarthrosis and no leg amputation. The considerably increased stability of the Vidal-Adrey double frame modification did not reduce the length of the healing period compared to fractures treated with bilateral Hoffmann frames. The duration of external fixation was on average 24 weeks, and the radiological healing time 27 weeks. A slightly greater number of residual deformities were found in the group treated with bilateral Hoffmann frames. Most of the deformities were so minor, however, that they were of little practical consequence for the patients. Thus it seems that the original Hoffmann apparatus, if duplicated, is a stable enough fixation in most cases.