In this present experiment we had studied about to evaluate in vitro anthelmintic activity of Rhizophora mucronata by using leaves extract. Anthelmintic activity was tested against Indian earthworm Pheretima posthuma. Extraction of Rhizophora mucronata demonstrated potent anthelmintic activity tested against Indian earthworm Pheretima posthuma. The dose-dependent anthelmintic efficacy of the fractions was quite similar to that of piperazine citrate The result obtained in the study led to the conclude that leaves of the mangrove plant, high level of polyphenolics and show significant anthelmintic activity.