A 35 year old woman developed a severe meningeal reaction after lumbar myelography using the water-soluble contrast medium methylglucamine iocarmate. Three months after myelography the findings were a transverse spinal cord syndrome corresponding to the middle thoracic segments resulting from well developed leptomeningeal adhesions. This was combined with a noncommunicating hydrocephalus, probably the result of leptomeningeal fibrosis in the posterior fossa. After treatment with a ventriculoatrial shunt the patient is almost free of symptoms. A possible pathogenetic relationship between the contrast medium, the chronic leptomeningeal changes, and the symptoms of our patient is discussed on the basis of the literature.