Abstract: Anthelmintics derived from plant source can be an answer to this world wide problem as they form secure and non-toxic with a modified site of action. Ocimum sanctum Linn known as Tulsi in India is a sacred plant for hindus known from centuries and being used in Ayurveda for its varied healing properties belonging to the Labiateae family. To this purpose we have studied in vitro antihelminthic activity of osmium in comparison with albendazole. The leaves of Ocimum sanctum was taken from the Institute staff quarter’s garden, which was endorsed by certified Taxonomist. The study was done using earth worms’ adult type due to their anatomical resemblance with the intestinal roundworm parasites of humans. The suspension of aqueous extract of leaves of Ocimum sanctum Linn, concentration 100 mg/ml was prepared. Albendazole was used as standard reference drug and its 20 mg/ml concentration was prepared by as per the prescribed method. The anthelmintic activity was performed according to standard screening methods. Aqueous extract of Ocimum sanctum took145±14 minutes to paralyze and 223+11 minutes to death of the worm, whereas Albendazole took 92±18 minutes to paralyse and 165±17 minutes to death of the worm with significant (P<0.05) value. Aqueous extract is more potent than control (NS) and lesser antihelmintic acvitity than albendazole. Time to paralysis and consequent death were significantly higher in aqueous extract of Ocimum that of Albendazole at same concentrations. Aqueous extract of Ocimum sanctum Linn is more potent than control (NS) and lesser antihelmintic acvitity than albendazole. Time to paralysis and consequent death were significantly higher in aqueous extract of Ocimum that of Albendazole at same concentrations.