A study on the effects of the anterior and the posterior column of the acetabulum on pelvic ring stability was carried out by applying a lateral compression force to specially prepared specimens. In group 1, the continuity of the right anterior column was disrupted by removing the acetabulopubic part of the anterior column; the posterior column was left intact in order to measure the strength of the posterior column. In group 2 the continuity of the right posterior column was disrupted by removing the ischioacetabular part of the posterior column leaving the anterior column intact in order to measure strength of the anterior column. The posterior column provided an average maximum strength of 759.43 +/- 229.51 N and the stiffness was 113.19 +/- 22.40 N/nm. The anterior column provided an average maximum strength of 2015.40 +/- 352.31 N and the stiffness was 301.57 +/- 98.67 N/mm. Thus the anterior column provides 2.75 times greater strength to the pelvic ring than the posterior column (P < 0.05). This finding may be important in open reduction and internal fixation of double column acetabular fractures.