A detailed examination was made of alterations induced by artemether in the tegument of juvenile and adult Schistosoma mansoni worms using scanning electron microscopy (SEM). Mice were infected with 80±10 S. mansoni cercariae. Mice were treated intragastrically with artemether at 21 and 49 days after infection with single dose of 400 mg/kg. Mice were killed 24 hours post-treatment. The worms were collected by perfusion, processed routinely and examined by SEM. In juvenile worm study, all schistosomules examined showed alterations in the tegument, characterized by intensive contraction, bending of the worm body backwards beneath the acetabulum, swelling of tegumental ridges which usually resulted in fusion of the ridges and also destruction of the oral sucker and acetabulum. In adult worm study focal damage of the tubercles on the tegumental surface of male worms was seen. In both male and female worms, there was focal swelling and fusion of tegumental ridges and in others with peeling and extensive swelling of the tegumental ridges. In the most severely damaged worms, Damage to the oral sucker was also seen in both male and female worms. The results demonstrate that artemether damages the tegument of juvenile and adult S. mansoni and thus results in their death.