The authors present a rare case of acute complete paraplegia due to a lumbar schwannoma. The clinical presentation, magnetic resonance imaging features, and management strategy are discussed. A 29 year-old man presented with acute complete paraplegia and bladder and bowel incontinence. He had a history of stable back pain and a 4-year history of lower-extremity numbness bilaterally. Magnetic resonance imaging revealed an enhancing extraaxial mass filling the spinal canal over two segments below the conus medullaris. An L1-3 laminectomy was performed and the tumor was completely removed. Pathological evaluation showed features characteristic of a schwannoma. The patient regained almost complete motor function after 6 months. To the authors' knowledge, this is the first reported case of acute complete paraplegia secondary to lumbar schwannoma. Possible mechanisms of this occurrence are discussed.