Background Flail chest in thoracic trauma is associated with significant complications and carries high morbidity and mortality. At present there is no standardized management plan for flail chest. The aim of this study was to determine the risk factors affecting morbidity, mortality, and length of stay in the hospital.Methods We evaluated all patients admitted to our trauma centre between January 2002 and December 2004. Age, presence of pneumothorax, trauma severity score (ISS), length of stay, lung contusion and deaths were recorded.Results There were 100 patients with a mean age of 52 (SD 19.8, range 17–90). The median length of stay was 17 days, and the average ISS score was 30 (SD 13.2). 74% had flail chest and lung contusion, 2 patients had pneumothorax, and 7 (7%) patients died 3 (5.4%) patients with 1–4 fractured ribs died, compared with 4 (8.9%) patients with 5 or more fractured ribs (p = 0.70, Fisher’s exact test). The mean ISS score was 32.3 (SD 19.5) for those who died compared with 29.8 (SD 12.7) in those who did not die (p = 0.63, t‐test). There was a moderate positive correlation between ISS score and length of stay (r = 0.36, p = 0.0002, Pearson correlation coefficient).Conclusion ISS score was found to be a moderate potential predictor on outcome regarding length of stay in the hospital. There is an apparent increased risk of death with more fractured ribs and therefore a standadised surgical management plan for ribs fixation may reduce the risk of death in this patient group.