A rare case of intramedullary holocord astrocytoma extending from the medulla oblongata to the conus medullaris is reported. A 27-year-old male who had been suffering from nuchalgia for a few years was admitted to our department because of lumbago and gait disturbance. Neurological examination revealed sensory disturbances in various locations, weakness of the right lower extremity, mild swallowing disturbance, and bowel and bladder difficulties. Magnetic resonance (MR) images and myelograms showed a long cystic lesion extending from the medulla oblongata to the thoracolumbar spinal cord. Gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA)-enhanced images detected a solid tumor located at the Th6-7 level. Two syrinx-subarachnoid shunts were placed at the upper cervical and Th12 levels. The solid neoplasm at the Th7 level was partially resected and histologically diagnosed as astrocytoma. Differentiation between cystic lesions and solid masses in the spinal cord is difficult. The usefulness of Gd-DTPA-enhanced MR imaging in the diagnosis of holocord tumor and the pathogenesis of secondary syringomyelia are discussed.