The present invention relates to an integrated process for processing and utilizing every part of the guayule plant (Parthenium argnetatum) which comprises the following steps in sequence: separating the stem and branches from the leaves of said plant with a mechanical treatment; treating the leaves to produce waxes and essential oils, and a fraction containing cellulose, hemicellulose (carbohydrates) and, to a minor extent, salts, organic compounds and lignin; extracting from the stem and branches a liquid phase, so forming a first solid woody residue, indicated with bagasse in the present text; treating said first solid woody residue to prepare sugars, resin, rubber and lignin.