This study presents the comparison between agricultural and forest resources related to the needs of biochemical processes. Recommendations and exchanges with future users (IFP, ARD) were used in this study. 234 samples from two years (2007-2008 and 2008-2009) were selected and analysed. Various species were analysed for their chemical composition, especially the content of fermentable sugars. Then the results were shown for homogeneous species groups: annuals immature, annuals mature, forage grasses, perennials harvested green in the fall and dry in late winter, hardwood and softwoods forest woodchips, short and very short rotation coppice. Common methodologies in the analysis and a database of samples for agriculture and forestry were used. The levels of hemicellulose were in the same range for both agricultural and forest biomass between 15 and 25% d.m. Regarding cellulose content, three groups could be distinguished: summer annuals and forage grasses (25 to 30 %), perennials and forest hardwoods and softwoods chips (38 to 46 %) and finally SRC and VSRC (52 to 54 %). In general, forest biomass contained more lignin than agricultural biomass: 20 % d.m. to 30 % d.m. while for agricultural biomass, values ranged from 8 to 20 %. Perennial crops contained more lignin than annual, between 15 and 20 % d.m. The agricultural biomass contained more C5 sugar and less C6 sugar, than forest biomass with the exception of perennials harvested dry in late winter.