The objective of the trial was to compare the safety and efficacy of the non-ionic, dimeric, isotonic contrast medium iodixanol (Visipaque 270 and 320 mgI/ml) with those of iotrolan (Isovist 300 mgI/ml) in myelography. After lumbar or cervical puncture, 315 patients were examined in a multicentre, double-blind, randomised, comparative myelography study. Image quality, changes in vital signs, immediate and delayed adverse events were registered. There was a tendency for better images with iodixanol 320 than with iodixanol 270 and iotrolan 300, but the overall quality was good or excellent with all products. The frequency of patients reporting adverse events and headache varied much across centres, but there was no statistically significant difference between the contrast media. The incidence of events was higher after lumbar puncture than after cervical puncture, in women rather than in men, and after puncture with a 22-gauge (G) bevel-tipped needle compared with a 24 G Sprotte needle. The frequency of headache did not correlate with the absence of pathology. The higher iodine concentration in iodixanol 320 could be an advantage for film quality. When compared with iotrolan 300, iodixanol 320 and 270 give similar incidences of adverse events, including headache.