Hepatic fibrosis was assessed by estimating hydroxyproline content in liver tissues at the course of the disease and after PZQ treatment. Parasitological investigations included egg count in faeces and tissues (liver and intestine) and oogram pattern. The results showed that treatment of infected mice with PZQ, modulated the course of schistosomiasis as evaluated by highly significant decline in hepatic hydroxyproline content as well as egg count in stool and tissues. In addition, the oogram pattern showed that PZQ had a lethal effect on mature eggs in tissues. PZQ treatment of S. mansoni infected mice, is effective in reducing the severity of the disease and in attenuating hepatic fibrosis, particularly when the treatment starts early with a suitable dose.