The meglumine salts of iodoxamic and iotroxamic acids are recently developed intravenous cholangiographic media. In several studies these two media have been shown to be significantly better than meglumine iodipamide and meglumine ioglycamate for opacification of the biliary tree and incidence of adverse effects. As part of a multi-centre double-blind trial 100 patients were given iodoxamate or iotroxamate. Comparisons of opacification, side effects and renal excretion of contrast were made. The results showed no statistically significant difference in biliary tree opacification; more frequent renal excretion of contrast with iodoxamate; and contrary to previous reports a slightly higher incidence of side effects with iotroxamate.