American Trypanosomosis is an important parasitic infection in Peru. Human cases, reservoirs and vectors have been showed in two known geographic areas in the endemic zones: southwestern and northern and northeastern regions of the country; however vectors belonging to the three genera of triatominae: Triatoma, Panstrongylus and Rhodnius have been collected in almost all the territory. The serological surveys in blood banks in the southwestern region is 2-6% and human cases found out of the endemic areas show the possibility of congenital cases. The study of the prevalence is starting. This preliminary study performed on 3000 pregnant of Arequipa shows serological positives in 22 (0.7%) and only a newborn positive at IgM. This result indicates a probable low rate of congenital transmission and necessary to perform more studies.