Praziquantel (40 mg/Kg.) and Oxaminquine (30 mg/Kg.) were administered orally to mice at seven weeks after infection with S. mansoni. The tegumental surfaces of non-treated as well as treated adult worms were examined by scanning electron microscope seven days after treatment. The surfaces of the worms were shown to be different from other studied strains. Such differences include; the devoideness of the female tegument of several sensory appandages; the number of sensory bulbs per papillae was high and the interpapillar setae were absent on the dorsal and dorsolateral surfaces of the male. Both drugs affected the surfaces of the male more pronouncedly than the female. Praziquantel was more effective in the destruction of spined papillae, wrinkling and disturbing the interpapillar spaces. Oxamniquine destructed the suckers, but had little effect on the spined papillae. No post-treatment recovery of worm's teguments was noticed.