48 injuries to the pelvis were treated from January 1991 through December 1991. We found 45 fractures of the pelvic ring with associated acetabular fractures in 15 cases and three isolated acetabular lesions. 19 injuries were caused by car accidents, 18 fractures resulted from a fall, especially in older patients. Isolated fractures of the pelvis occurred in 18 cases. The average total severity of the injuries was 19.7 points according to the Hannover Polytrauma Score (PTS). Every fracture was classified using the Tile-classification. There were 15 (33%) Tile A lesions, 18 (40%) Tile B fractures and twelve (27%) type C pelvic ring injuries. In 18 cases surgery was the method of treatment. Seven out of 18 injuries to the acetabulum were treated with open reduction and internal fixation. In ten patients the unstable pelvic ring was fixed by means of an external fixator. To do so, a pair of 6 mm diameter pins were placed on both sides in the supraacetabular region of the iliac bone directed towards the sacroiliac joints. We used a triangular form of external fixation. An open reduction and internal fixation (ORIF) was necessary in five cases, one injury required a combination of external and internal procedures. There were 14 cases in which we found sacral fractures as an additional dorsal lesion. Nine of 14 sacral fractures were recognized only by CT examination. In eleven cases the conventional radiographs showed simple anterior pelvic ring fractures while the CT examination revealed an additional lesion of the sacroiliac joint in nine of these cases.(ABSTRACT TRUNCATED AT 250 WORDS)