Commercial injectible contrast media based on iothalamate, diatrizoate, iodipamide, and acetrizoate were analyzed for inorganic iodide. The method utilized extraction of the iodide as iodine, followed by conversion to iodate and titration of the iodate. Reliable and reproducible results were obtained with all except the diatrizoate media. Values ranged from 0.6 to 8.3 mg % iodide. Sodium salts were lower in iodide than methylglucamine salts. Indoor light or heating at 45° in the dark had little or no effect. Exposure to sunlight resulted in very large increases in iodide content and other changes.