Abstract: Human schistosomiasis is the second most prevalent tropical disease after malaria and has considerably public health and socioeconomic burden in developing world. The only drug available for treating schistosomiasis is praziquantel, however it lacks efficacy against schistosomulae and there are already reports of resistance to its use in treatment, making it necessary to explore and upsurge for new compounds to combat schistosomiasis. This study was designed to evaluate anti-Schistosoma activity of the methanolic extract of Plectranthus tenuiflorus (Vatke) Agnew; an herb on different stages of Schistosoma mansoni. Parasite viability and morphological changes were assessed after incubation with different dilutions of the plant extract using inverted as well as scanning electron microscopy. Plectranthus tenuiflorus (Vatke) Agnew extract showed moderate anti-cercaria and anti-schistosomulae activity with calculated IC50 12.29 and 17.39, respectively compared to lesser anti-miracidium activity with IC50 24.37 mg/100 mL. This is the first study to assess anti-schistosoma potency of Plectranthus tenuiflorus (Vatke) Agnew extract and may suggest a promising medicinal constituent of Plectranthus tenuiflorus (Vatke) Agnew extract importantly against cercaria infective stage and the significantly ambulant invasive Schistosomulae inside human body which impose further studies to evaluate different extracts and fractions of this plant.