An accurate and rapid radiochemical method has been developed for the determination of microgram amount of silver employing potassium ethyl xanthate as a Substoichiometric radiochemical reagent. The light yellow coloured silver ethyl xanthate formed was extracted into nitrobenzene from sulphuric acid media. The effect of foreign ions on the extraction was studied. The method was applied to the determination of silver content in photofilm washings.