The changes in the content and forms of organic matter and nutrients in fresh and 3-month stabilized FYM were examined. The maturity process produced a significant increase in total N, water-soluble substances and lignin contents, and a decrease in C, lipid and hemicellulose plus cellulose contents as well as in the C/N ratio. All these characteristics can be considered as useful maturity parameters. The various analyses used to assess the content and forms of humified substances failed to show significant differences. It was concluded that the FYM obtained after a 3-month stabilization process is still insufficiently humified. The nutrient elements content increased, and the availability generally decreased, with the maturity.