Male and female mice of ACA strain were infected with 200 and 2,000 bloodstream trypomastigotes from Dm 28c clone of Trypanosoma cruzi. All the animals were susceptible to the infection regardless of their sex and dose of initial inoculum used. Both male and female, infected with 2,000 parasites showed significantly higher level of parasitemia than mice infected with the lower dose. At the same time, males developed higher parasitemia level than females, when they were infected with both 200 and 2,000 parasites. Despite of experimental animals behaved as susceptible, the survival period was significantly longer in males infected with 200 trypomastigotes when compared to males infected with 2,000 parasites. Females infected with 2,000 survive a longer time than males infected with the same dose of parasites. No significant differences were observed during the survival period when comparing females infected with 200 and 2,000 parasites, neither in the case of male and female infected with 200 parasites. Apparently, the parasitemia level is the main characteristic affected by the variables sex of the host and initial parasite dose.