Eight out of 46 strains of Streptomyces isolated from mural paintings in the Tell Basta and Tanis tombs were exposed to various doses of gamma radiation (5, 10, 15, 20, 25 kGy). Tricyclazole (5, 7, 10 µg/mL) in dimethyl sulfoxide (DMSO) at 10 µg/ mL completely inhibited melanin production in Streptomyces spp. after their gamma irradiation to sub-lethal doses. FT/IR spectra proved that the gypsum support, the binding media (which consisted of Arabic gum, and animal glue), and pigments all had withstood the doses up to 25 kGy, with except vermillion showed slight change. No efect of gamma irradiation up to 25 kGy on gypsum support was detected, so gamma irradiation could be considered a safe method for decontamination of biodeteriorated cultural heritage objects.