Results of the experimental infections of the iaboratory bred rodent Calomys callosus are presented in th is paper. The following parasites were as infective agents: Plasmodium berghei, Leishmania mexicana amazonensis, Schistosoma mansoni and Hymenolepsis nana. C. callosus was refractory to H. nana while it has shown to be susceptible to the other three parasites. The infection rates for each one this parasites was 80 per cent. C. callosus has been maintained under laboratory conditions for six generations showing excellent adaptation and easy handling. It is believed that this animal can be used as laboratory experimental model for certain parasitic diseases.