The goal of the study was to determine total Hg and Hg species in seafood samples comprising fish, crustaceans and bivalves. The study focused on the extraction, identification and accurate quantification of MeHgþ, the most toxic form, which was selectively separated and determined by liquid chromatography coupled to on-line UV irradiation and cold vapour atomic fluorescence spectroscopy (LC-UV-CV-AFS). Sample preparation was optimized to be as simple as possible, but still provide adequate sensitivity and specificity for the routine analyses of seafood.