In vitro activity of aqueous and alcoholic extracts of the plant Calotropis procera (6.25, 12.5 and 25 mg/L) have been applied against Schistosoma mansoni adult worms. The mortality of adult worms was observed after exposure to aqueous and ethanolic stem extracts of C. procera during a period of 48 hours. The ethanolic extract of C. procera (at 25 mg/L) caused death of all worms after only half an hour. However, the concentration of 12.5 and 6.25 mg/L caused death of all tested worms after three hours of exposure to the ethanolic extract. On the other hand, the exposure of Schistosoma mansoni adult worms to the aqueous extract of C. procera (at 25 mg/L) caused death of these worms after four hours. In aqueous stem extracts, a dose of 6.5 and 12.5 decreased the worm viability in comparison with control. Moreover, in all concentrations of both aqueous and alcoholic extracts, coupled adult worms were separated into individual males and females. Alterations of male worms' tegument exposed to ethanolic and aqueous extracts in comparison with control worms were examined by scanning electron microscopy. In conclusion, C. procera alcoholic extract has a more schistomicidal activity than aqueous extract. In addition, it has been found that C. procera extract induces marked effects on tegumental surface architecture.