Acute traumatic L5–S1 spondylolisthesis is a rare condition, almost exclusively the result of major trauma, frequently associated with L5 transverse process fracture and neurologic deficit. In recent years, open reduction and internal fixation with posterior stabilization has been the method of treatment most frequently reported. In the current case, the lesion was found in a victim of an automobile accident. Signs of a right L5 root deficit but no sphincter dysfunction were present. A computed tomography scan revealed several fractures in the posterior parts of L5 and anterior displacement of L5 on S1. A magnetic resonance imaging (MRI) scan verified that the lesion was indeed acute by showing the ruptured L5 disc and posterior ligaments, thereby demonstrating the importance of MRI in the planning of the treatment of these lesions. This case was successfully treated with an acute circumferential instrumented L4–S1 spondylodesis.