Arsenic (As) stabilization using zerovalent iron (Fe0) and its combination with peat was investigated in soil used as a pilot scale landfill cover in Northern Sweden. Leachate percolating through a 2 m thick layer of treated and untreated soil was collected in field. Chemical fractionation using sequential extraction, phytotoxicity test with dwarf beans and bioaccessibility tests simulating gastric solution were performed to assess the residual risks to the environment and human health. The results show that the exchangeable As-fraction in stabilized soils decreased when compared to the untreated soil, while other fractions remained unaffected. All the morphological parameters of plants improved and the bioaccessible As-fraction significantly decreased in the Fe-peat treated soil. The analysis of the leachates collected in field showed a substantially decreased As concentration in the Fe-peat amended soil. Further sampling is on-going in order to determine whether or not the treatment is successful in a long-term.