Dissolved organic matter (DOM) generated from decomposition of plant debris plays a critical role in soil weathering and the podzolization process. It is believed that dissolution and translocation of soil iron and manganese is principally of chemical reaction in which carboxylic and phenolic acids attack Fe/Mn minerals and form soluble organo-metallic complexes. In cool, moist environments such as thick leaf-overlaid forest floors in the rain season, however, an anoxic condition may develop and microbial reductive release of soil Fe and Mn be dominant. The role of DOM in facilitating the development of anaerobic conditions and subsequent dissolution and leaching of soil Fe and Mn was evaluated. An iron-rich Hapludult was incubated in sealed vessels with DOM extracted from moderately decayed deciduous tree leaves for 20 d, with and without the addition of 200 mg L-1 sodium azide. The soil was further packed into columns and saturatedly leached with the DOM solutions for 30 d. The redox potential of azide-amended systems was much higher than those without azide amendment, indicating inhibition of microbial reductive activities in the former. In both batch and column experiments, release of Fe and Mn from soils treated with DOM alone greatly exceeded that from soils treated with both DOM and azide or with azide alone. The results suggest that under anaerobic conditions, DOM promotes dissolution and leaching of soil iron and manganese mainly via stimulating microbial reductive activities.