We have experienced a rare case of leukemic lesion(chloroma) in the lower spinal canal which was confirmed by the surgery and histologic examination of the tumor. A farmer, aged 39, was admitted to the Department of Neurosurgery, St. Paul Hospital in December 1974 with chief complaints of low back pain with radiating pain in the right lower extremity and voiding difficulty for one month. On admission, neurologically, the patient exhibited weakness of the right anterior tibialis, extensor hallucis longus and peroneus longus and brevis muscles and sensory involvement of the right third, fourth and fifth sacral dermatomes. He was disclosed the positive signs of the Naffziger's and Lasegue's and severe tenderness on the spinous process of the fifth lumbar and first sacral vertebrae. Lumbar myelogram demonstrated a total block at lower level of the fifth lumbar vertebra and a filling defect of the right fifth lumbar root area. Through the laminectomy of fourth lumbar to first sacral lamina, an extradural greenish soft mass located at the ventral aspect of the right fifth lumbar to upper sacral roots, and the mass was removed. The biopsy specimen disclosed chloroma with leukemic infiltration of the meninges.