Objective To investigate the incidence and treatment of posttraumatic cauda equina herniation associated with lumbar fracture.Methods A retrospective analysis was performed on 416 patients admitted due to lumbar burst fracture between June 1,2008 and June 1,2011.All the patients had been operated on via anterior or posterior approaches.Data collected included demographics,injury mechanism,radiographs,surgical procedures,outcomes and follow-up.Incidence of cauda equina herniation was documented.Results All surgeries were uneventful.Cauda equina herniation was observed in 49 patients (11.8％) during surgical exploration.Anterior surgery was done on 115 patients and found 7.8％ incidence of cauda equina herniation (9/115).Posterior surgery was done on 301 patients and found 13.3％ incidence of cauda equina herniation (40/301).There were 40 patients combined with laminar fracture and 38 of them had cauda equina herniation with the incidence rate of 95％.Among the 49 patients with cauda equina herniation,44 (90％) had neurological deficit and 5(10％) were found with good neurological function but significant proportion of cauda equina rootlets entrapped in the lamina fracture.Conclusions Lumbar burst fracture combined with neurological deficit and laminar fracture may increase the risk of posttraumatic cauda equina herniation and should be paid attention.Operations should be performed with caution to avoid further nerve damage.