The aim of this study was to examine how commonly implicated prognostic factors are associated with late clinical outcome after reconstruction of acetabular fractures. The clinical outcomes of 180 fractures, treated by a single surgeon over a 10-year period, were assessed using the scoring system of Merle d'Aubigné and Postel. A statistical model was constructed comprising the clinical outcome and nine postulated prognostic factors. The association between these factors and sub-optimal outcome was explored by logistic regression and log linear analysis, and a model of causality was postulated. Associated fracture type, imperfect reduction (3mm), the presence of local complications and heterotopic bone were prognostic factors independently associated with a sub-optimal outcome. The sex or age of the patient, the presence of hip dislocation, sciatic palsy, or an interval from injury to surgery of 1-18 days were factors which were not directly associated with a poor outcome. Imperfect reduction was itself affected by associated fracture type and increasing age, and it is the latter connection that may explain any apparent association between sub-optimal outcome and increasing age.