a comparative study was done between dipetalogaster maximus uhler infected with strain y of trypanosoma cruzi chagas and uninfected, in order to know the interspecific relationship between the host insect and the protozoan parasite, by the establishment and remaining of the infection during the triatomine life cycle. this information is essential in constitution of trypanosomes strains banks, to be preserved in vector insect. the triatomines were bred (28±1oc, 70% of relative humidity with photophase of 12h) and separated in groups of 60 insects for each experiment. in one group, 1st instar nymphs of d. maximus were infected with y strain of t. cruzi, with approximately 2,2x105 trypanosomes, on the 10th day after hatch. medium period for nymphal development including 30 days for incubation of eggs was 201.1 and 204.8 days for uninfected and infected males and 202.5 and 204.2 days for uninfected and infected females. medium fecundity was 217.4 and 231.0 eggs for uninfected and infected females. medium fertility was 60.4% for infected females and 66.3% for uninfected females. medium number of eggs per oviposition was 2.9 eggs for infected females and 2.7 eggs for uninfected. medium amount of blood ingested to accomplish nymphal development of d. maximus was 4970.4 and 4901.3 mg for infected and uninfected insects. medium longevity was 513.5 and 504.5 days for uninfected males and females and 489.8 and 463.0 days for infected males and females. the interspecific relationship between d. maximus and t. cruzi was harmonic during the insect life cycle.