From 12. 1988 to 6. 1990 we carried out on 27 patients at the Department of Gynaecology of the University of Freiburg an open study to compare the two water-soluble, nonionic, monomeric contrast agents (Iopamidol-300 corresponding to Solutrast-300 and Iopamidol-370 corresponding to Solutrast-370) with different osmolality (616 mosm/kg H2O resp. 799 mosm/kg H2O) and concentration (300 mg I/ml resp. 370 mg I/ml). It is a remarkable fact that the contrast quality in the x-rays was higher for Iopamidol-300. Complications such as hypersensitivity reactions or local irritations were not recorded. Iopamidol-300 was found to be the best tolerated of the two contrast media in respect of mildest intensity of pain.