This study aims to test the action of three different compounds acting as CP inhibitors (CPIs) namely fluromethylketone (FMK), vinyl sulfone (VS) and sodium nitro prussid (SNP). These specific irreversible inhibitors of CPs inhibit the degradation of hemoglobin (Hb) in developing schistosomula, eventually resulting in worm death and reduce egg production. These inhibitors may recently used as new chemotherapeutic drugs for treatment of schistosomiasis. This work trial to study the possible additive or synergistic effect of both PZQ and these CPIs on susceptible strains of S. mansoni infected albino mice. This study will be applied both in vitro and in vivo.