ABSTRACTProduction of mushrooms and wine has a very significant economic impact on the Region of La Rioja (Spain). A direct consequence of these activities is the production of large volumes of agricultural wastes. Since composting may be a viable alternative means to reduce the environmental problems currently associated with the management of these residues, this article reports the results that have been obtained from the composting of two types of spent mushroom substrate and winery sludge. The characteristics of the final product indicated that this combination of residues results in an organic material that is suitable for application to crops.