During the processing of antimony ore by pyrometallurgical methods, a considerable amount of slag is formed. This antimony waste slag is listed by European Union as absolutely hazardous waste with European Waste Catalogue code of 10 08 08. Since the levels of antimony and arsenic in the leachate of the antimony waste slag are generally higher than the landfilling limits, it is necessary to treat it before landfilling. In this study, stabilization/solidification and geopolymerisation technologies were both applied to limit the leaching potential of antimony and arsenic. Different combinations of pastes by using Portland cement, fly ash, clay, gypsum and blast furnace slag were prepared as stabilization/solidification or geopolymer matrixes. Sodium silicate-sodium hydroxide solution and sodium hydroxide solution of 8M were used as activators for geopolymer samples. Efficiencies of the combinations were evaluated in terms of leaching and unconfined compressive strength.