Sixteen mice were tested with the crude extract of the seed of Thevetia neriifolia. Local effect of the crude extract showed thinning of the stomach wall and that of the small intestine. Histopathological study showed congestion of blood vessels in heart, lungs, kidney, liver and spleen. Haemorrhages are seen in heart and liver. The mode of action of Thevetia neriifolia is discussed and further investigation is in progress for the purpose.