Melamine formaldehyde resins, widely used in various industries, are thermosetting plastics that have hard and durable properties. These resins can be introduced into the environment as components of waste products or via industrial effluents. It is important to seek environmental friendly means to recycle, remove or degrade melamine resins before they are released to the environment. In this study, the impacts of C/N ratios on windrow composting of paint sludge containing melamine resin were evaluated. As composting proceeded, temperature, concentrations of melamine resin and its degradation products, and changes of genes that regulate the production of enzymes catalyzing the degradation of melamine degradation products (i.e. ammeline, ammelide and cyanuric acid) were determined. Melamine resin degradation after 98 days of composting varied between 70-85% for the different C/N ratios of composting. It was concluded that windrow composting of melamine resin in paint sludge is an environmental friendly means to convert the paint sludge into a value-added product.