The present work performed to study the toxic effects of the crude plant extracts of Croton tiglium seeds on some histological changes of the terrestrial snail species M. obstructa. The molluscicidal efficacy of ethanol and acetone extracts of Croton tiglium seeds were tested against the adult snails of Monacha obstructa (L. Pfeiffer) (Gastropoda: Hygromiidae) at four concentrations using contact technique under laboratory conditions for seven days. Also, the impact of crude seed extracts was studied on some histological changes of the land snail, M. obstructa. The results revealed that the hexane and ethanolic extracts of croton exhibited molluscicidal activities against M. obstructa land snails. The ethanolic extract displayed the highest potency where LC50 was (0.08 %) while the LC50 of hexane extracts was (0.12 %). Histological inspections of the digestive gland and foot of snails exposed to LC50 croton extract showed that the digestive tubules showed various destruction, shrinkage in different types of cells lining the digestive tubules, marked increase in the width of most of the digestive tubules lumen and filled with secretory materials, rupture of basement membrane and the intertubular loose connective tissue between the digestive tubules showed necrosis. The histological alterations in the foot included rupture of the epithelial covering with necrosis, destruction of muscular tissue and necrosis of connective tissue with presence of dark brown pigment. Thus, these results indicated that croton seed crude extracts possessed molluscicidal potential for controlling the land snail with more future studies to develop and ensure its wider applicability as a molluscicide
