The chemical screening of the biomass of a new marine-derived strain of Penicillium roqueforti, produced by liquid-state fermentation, led to the identification of several volatile and nonvolatile compounds. As a result of previous studies, we have isolated and characterized a new molecule. The chemical structure of 2-deoxy-2-phosphamino-alpha-D-glucopyranose isolated was elucidated on the basis of 1D and 2D NMR studies together with other instrumental techniques. As a result of this discovery, a biogenetic route has been proposed to explain its formation as an intermediary component of the chitin biosynthesis.