To know the biological characteristics of a strain of Trypanosome cruzi, coming from the district of Tiabaya, Arequipa, Peru, and to determine the survival of inoculated mice relating the infecting dose ante and sex. Were used 14 BALB/C-53 mice (males and females) of 30 days of age as biological model. The groups I and II were inoculated via intraperitoneum with 1,8 × 105 and 1,8 × 104 meta-cyclic trypomastigotes of T. cruzi, respectively; group III with 1,5 × 107 sanguine trypomastigotes. Control group (IV) received only physiologic saline solution at 0.9%. The parasites were searched in peripheral blood of the mouse. The analysis of survival was carried out by Kaplan-Meier method, Logrank test and Wilcoxon to 95% of confidence level. Were find thin and thick forms of T. cruzi. The fatality rate was 100% groups at day 40 -post-infection- (pi). The parasitemy was detected from the 6th until the 40th day pi and the global maximum pick (6747 parasites) was observed on the 29th day pi. Significant differences exist in the survival of inoculated mice according to the dose by the Logrank test (p = 0,0202). The strain of T. cruzi, coming from Tiabaya, Arequipa is of medium virulence. The survival of the infected mice is related to the dose of inoculation.