An open, non comparative study of cervical myelography in 68 adult patients using iohexol (Omnipaque) containing 300 mg I/ml is reported. Satisfactory visualisation was achieved in all cases. Minor adverse effects occurred in 13 patients (19%); they were headache (8), neck or back pain (3), vomiting (3), nausea (1), dizziness (1) and nystagmus (1) and were of minor degree in most and moderate in a few, lasting more than 24 hours in only one patient. EEG performed in 39 patients before and 24 h after the myelogram showed no seizure activity or significant change. Iohexol is a very satisfactory drug for all types of myelography.