An analytical method for simple and rapid determination of methylmercury in sediment and organism samples is described. The proposed method employs the oxygen combustion-gold amalgamation using Direct Mercury Analyser (DMA-80) after complete removal of MeHg by organic extraction and back extraction to an aqueous medium. DMA-80 instrument is equally suitable for the analysis of solid and liquid materials and has a good detection limit. The analytical performance of this method was evaluated by analysis of certified reference materials (CRM-580, IAEA-405, DORM-2, DOLT-3, SRM-2976 and SRM-2977) assessing its quality in terms of accuracy, repeatability and quantification limit. Furthermore total mercury and methylmercury have been analysed in sediment and organism samples collected during the XXI Italian Antarctic Expedition in Terra Nova Bay (Ross Sea, Northern Victoria Land). The results obtained show the validity of the proposed method as ready-to-use analytical method to analyse real samples.