Lumbosacral dislocation is uncommon. We report a case of traumatic lumbosacral dislocation which occurred in a 33-year-old pedestrian traffic accident victim. The posterior impact produced lumbar injury with diffuse pain exacerbated at the lumbosacral junction. Ecchymotic diffusion involving the entire lumbar region fluctuated due to the presence of a subcutaneous hematoma. The neurological examination revealed incomplete L5 paraplegia. Standard x-rays revealed L5-S1 spondylolisthesis and fracture of the L5 spinous process as well as fractures of the L3, L4, and L5 transverse processes. Computed tomography disclosed biarticular L5-S1 fracture dislocation and a voluminous herniation of the L5-S1 disc. Emergency surgery was performed and revealed subaponeurotic detachment from T4 to S1 and bald iliac pyramids. After L5 laminectomy and extraction of the voluminous herniation of the L5-S1 disc, a short L5-S1 posteriolateral fusion was achieved using pedicular screws and two rods on either side as well as a posterolateral iliac autograft. The clinical course was satisfactory with nearly complete neurological recovery (persistent levator ani paresis). This clinical case and a review of the literature illustrate the pathogenic, clinical, radiological and therapeutic aspects of lumbosacral fracture dislocation.