Introduction: Hydatid cyst is among parasitic diseases common between man and domestic animals, as well as domestic and non domestic carnivorous animals. This disease causes organ damage and injuries in human, and sometimes leads to death. This study aims at assessment of secondary hydatid cyst growth in laboratory animals and determination of their sensitivity.Materials and Methods: The Present study was carried out to find the sensitivity of white mice and hamster for secondary Echinococcus using Echinococcus granulosus protoscoloces obtained from Iranian sheep.36 male white mice (NMRI Strain), 27 male hamsters (albino variety) both were injected intraperitoneally with E.granulosus protoscoloces.White mice and hamsters each received 1000 and 10000 the protoscoloces respectively.During 9 months, 4 mice and 3hamsters were killed each month and their liver, lung, peritoneal cavity, kidney and spleen were examined for presence of hydatid cyst. Findings: Secondary hydatid cysts were found in mice after 3 months past inoculation and after 9 months all the mice became infected. By rising the period of infection, the number of positive infected mice and number of the cyst increased significantly in 2 mice (8 and 14 cysts found in peritoneal areas of them).Conclusion: Hydatid cyst did not develop in hamsters all cysts were found sterile and infertile.