Experiences with the nonionic contrast medium Optiray 300 were analyzed in 120 consecutive patients who underwent intravenous urography. Allergic diathesis was recorded prior to the examination in 12.5% of the patients, pretreatment was given in only 3 cases. The clinical safety of Optiray was outstanding, no adverse reactions were noted. Diagnostic quality of the radiographs was excellent in 78% and good in 22% of the cases. Optiray is considered to be a safe and effective contrast agent for use in intravenous excretory urography.