This study sought to determine the Efficacy of Allamanda cathartica leaves crude extract as an antihelminthic agent. The researchers would like to prove if the constituents of Allamanda cathartica crude extract can eradicate the worms Ascaris suum) in vitro. The leaves of Allamanda cathartica was prepared as crude extract (50% and 100%) and was tested against pig roundworms (Ascaris suum) The worms are placed in a petri dish and the researchers observe for the number of worms died in every two hours interval. The positive control which is the Albendazole eradicated 5 worms within 2 hours. The Negative control which is the Phosphate Buffered Saline does not eradicate any worms within 12 hours. The experimental control which is the Allamanda cathartica (Yellowbell) which is 50% concentrated eradicated 3 worms within 2 hours and 2 worms after 4 hours. The data’s were presented by comparing the positive control from the experimental control and the negative control from the experimental control by using independent t-test. Based from the results, the Allamanda cathartica (Yellow bell) crude extract is effective as an antihelminthic agent.