Abstract: The present paper deals with the molluscicidal activity of dried powder of latex and stem bark of Euphorbia tirucalli (Family- Euphorbiaceae) against fresh water snail Lymnaea (Radix) acuminata Lamarack and Indoplanorbis exustus (Deshyas) and anticholinesterase activity of Euphorbia tirucalli latex and stem bark in the nervous tissue of Lymnaea acuminata. Both the snails are the vector of liver fluke, Fasciola hepatica Linnaeus and Fasciola gigantica Cobbold, which causes endemic fascioliasis in cattle and livestock. The toxic effect of the latex and stem bark powder was both time as well as dose dependent. There was a significant negative correlation between LC50 values and exposure periods thus increase in exposure time, the LC50 values of Euphorbia tirucalli latex was decreases from 0.92 mg DWL‾1 (24 h) to 0.51 mg DWL‾1 (96 h) against Lymnaea acuminata and 1.42 mg DWL‾1 (24 h) to 0.55 mg DWL‾1 (96 h) against Indoplanorbis exustus. Similar trend was also observed in case of stem bark powder. Treatment of sub-lethal doses (40 and 80% of LC50) of latex and stem bark powder of E. tirucalli also shows significant (P<0.05) time and dose dependent inhibition in the activity of enzyme acetylcholinesterase (AChE) in the nervous tissue of Lymnaea acuminata after 24 h or 96 h exposure periods. Withdrawal study also shows that there is a significant recovery in the acetylcholinesterase activity in the nervous tissue of snail after the 7th day of the withdrawal of treatment. Dried powders of latex and stem bark powder of E. tirucalli at higher doses were also lethal to fresh water fish Channa punctatus (LC50 24 h: 9.01 mg DWL‾1), which shares the habitat with these snails, but the doses LC90 (24 h) of snail did not cause any mortality among fish in a mixed population of snails and fish. It is proposed that the latex and stem bark powder of E. tirucalli can be used as a molluscicide for controlling the snails.