Objective. To specify the role and indications for application of аpparatus of external fixation (АEF) in treatment of unstable pelvic osseous injuries (UPOI); to study up the advantages and faults of the external fixation method; to share the experience of treatment, using this procedure.
 Маterials and methods. There were 229 patients, suffering pelvic injuries, examined on the base of orthopedic-traumatological centre of Kyiv’s Regional Clinical Hospital in 2005 - 2017 yrs and distributed into three Groups. In Group I 143 (62.4%) injured persons were included, in whom external osteosynthesis played the function of temporary measures of fixation, in Group II - 27 (11.8%) patients, in whom while hospitalization a fracture was fixed, using AEF, аnd after stabilization of the state the posterior pelvis osteosynthesis and reposition was conducted, in Group III - 59 (25.8%) patients, who, using several indications, were definitely treated, applying the external fixation method only.
 Results. Excellent effect of treatment in Group I was registered in 23 (19.0%), a good one - in 58 (47.9%), satisfactory - in 32 (26.4%), poor - in 8 (6.6%) of 121 patients; in Group II - accordingly, - in 5 (20.8%), 11 (45.8%), 7 (29.2%) and 1 (4.2%) of 24 patients; in Group III - accordingly, in 4 (8.3%), 12 (25%), 23 (47.9%) and 9 (18.6%) of 48 patients.
 Conclusion. Best results of treatment of patients with unstable pelvic osseous injuries were obtained while applying the tactics of change from external fixation into internal one. On the first stage the pelvic ring fixation, using AEF, was performed, аnd after stabilization of a patient general status - internal osteosynthesis. Application of the internal osteosynthesis method permits to control and stabilize the reposition achieved, to conduct the sacro-ileal joint revision.