An eight-month-old infant with diastematomyelia, as a very rare variety of spinal dysraphism is presented in this article. The introduction deals with a detailed description of diastematomyelia, its development, local, neurological, and orthopedic signs in affected patients, diagnostic procedures and significance of neurosurgical treatment in patients with diastematomyelia. In the particular child, immediately upon birth, a thornlike bulging was noticed in the L2-L3 region. Neurological deficit, established at the time of surgery, was due to the perinatal brain damage and corresponded to the spastic syndrome of the central origin with the right-hand side predomination, and there was no predomination in the lower extremities, which could be expected in regard to the spinal dysraphism. Plain X-ray film revealed a thornlike bulging at the L2-L3 level. Lumbar myelography showed a distinctly enlarged dural sac at the level of L2 to S1 with a well pronounced contrast medium passage defect at the L3 level. The spinal canal CT-findings revealed a bony bulging between L1 and L2, starting from the posterior arches towards the spinal canal. Besides a markedly broadened lumbar spinal canal, MR-findings also showed a well pronounced bony septum from the L2 posterior edge, and a low-lying conus medullaris with an accompanying spinal lipoma. By the neurosurgical operation bony septum and extradural lipoma were radically removed, and the spinal cord was set free from adhesions. In that way a later onset of neurological signs, due to the "tethered cord syndrome", was prevented. Six months following surgery the child's condition was still unchanged.