This document describes a method for the determination of organomercury in seafood/fishery products by elemental mercury analysis. The method has been successfully valideted in an interlaboratory study with a working range from 0,013 mg/kg to 5,12 mg/kg (HORRAT values <2) in seafood/fishery products [1], [2]. The limit of quantification is approximately 0,010 mg/kg organomercury (referring to dry weight, expressed as mercury) [3], [4]. Organic species of mercury, other than monomethylmercury, are also extracted and thus determined with this method. However, in seafood/fishery products the contribution from organic species of mercury other than monomethylmercury is negligible.