Chitin(poly(1,4)-2-acetylamino-2-deoxy-beta-D-glucan), which is abundantly obtained from the exoskeletons of arthropods, as well as its deacetylated derivative chitosan find increasing use in various areas. Extensive investigations have been undertaken on the application of chitosan in textile industries, such as surgical sutures, antimicrobial finishing of cotton and antistatic treatment of polyester. Treatments with chitosan have been found to improve the dyeability of cotton, wool, silk and leather with direct, acid or reactive dyes. Chitosan has a cellulose like structure with amino functions at C₂carbons. Once adsorbed on fibers, it enhances the uptake of anionic dyes. A wide variety of fluorescent agents are used for whitening textile. A high affinity for fibers, high intensity of fluorescences and photostability are required of practical fluorescent agents. In contrast to dyestuffs little has been studied on the interaction between fluorescent agents and chitosan. In this work we investigated the effect of chitosan on the ultraviolet and fluorescent spectra and photofading of fluorescent agents of a pyrazoline type in aqueous solution as well as on cotton and silk.