Despite its reduced use since the advent of magnetic resonance imaging, the high cervical myelogram remains a common diagnostic test in the evaluation of patients whose symptoms suggest cervical stenosis. We report a case of subarachnoid hematoma, hydrocephalus, and aseptic meningitis after a high cervical myelogram. A 52-year-old woman presented with headache, slurred speech, worsened neck pain and stiffness, and diffuse extremity weakness leading to gait instability beginning several hours after a cervical myelogram. Computed tomography (CT) scan revealed a C1-C2 hematoma below the dura, blood in the fourth and lateral ventricles, and hydrocephalus. An external ventricular drain was placed, and cerebrospinal fluid profile was consistent with aseptic meningitis. A suboccipital craniectomy and C1-C2 laminectomies were performed, followed by a C1-C2 durotomy, which revealed a large subarachnoid blood clot in the region of the cisterna magna extending down to the upper aspect of C2, which was evacuated by incising the arachnoid. In the midline at C1, an active source of intramedullary arterial bleeding on the dorsal surface of the spinal cord was coagulated. Spinal subarachnoid hematoma is a rare complication of high cervical myelogram. The extension of blood into the ventricular system with associated hydrocephalus has never been previously reported after myelography. Thus, severe persistent pain after cervical myelography should be evaluated by CT scans of the brain and cervical spine.