Paper materials, including chitosan-coated papers, display ahigh chemical and morphological heterogeneity, because of thecomplexity of the interactions among cellulose fbers, fillers andchitosan. Since we felt that these intricacies had not been ade-quately tackled by previous studies, we decided, within the contextof a wider research project on novel chitosan-based materials, tolook into this topic in a more systematic fashion, calling uponthe use of a fluorescent chitosan derivative as a tool to assess itsspatial and in-depth distribution onto the paper sheet. Althoughfluorescent chitosans have been applied to some biologically re-lated systems , to the best ofour knowledge, they were never reported as additives to paper.