Imaging of the spine is a fundamental part of assessment of paraparesis. Since the advent of MRI the indications for myelograms have diminished. However, a myelogram, although an invasive test, should still be considered a useful investigation for localising lesions in the spinal cord and for identifying rare causes of myelopathy. This case illustrates how a CT myelogram identified an arachnoid cyst, which is a potentially treatable cause of paraparesis.