The latex of four plants belonging to the family Euphorbiaceae viz.Jatropha gossypifolia, Euphorbia royleana, Euphorbia antisyphliticaandEuphorbia lactea cristatacaused significant reductions in the acid and alkaline phosphatase activity in nervous tissue of the snailLymnaea acuminata.The reduction in the activity of both the phosphatases was time and dose dependent; the order of effectiveness was as follows:Euphorbia lactea cristata > Euphorbia antisyphlitica > Euphorbia royleana > Jatropha gossypifolia.