Available mounting media cause fading of histological preparations over time. A study was designed to find the most suitable medium for durable mounting of Araldite embedded semithin sections of rabbit cerebral cortex stained with toluidine blue and pyronin G. Among four synthetic mounting media tested, only DePeX prevented fading of the sections during the first month. All mounting media tested helped preserve staining intensity after one month, since the fading rate after one year is only about half that in sections prepared without mounting medium. The average optical density of sections after one year was higher in preparations mounted with DePeX than in sections treated with the other mounting techniques tested in this study. After one year, the average optical density of sections mounted with DePeX had decreased approximately 20%.