Panstrongylus diasi Pinto & Lent, 1946, previously known from throught the Brazilian center-west, is reported for the first time in Mato Grosso state, Brazil. We found 3 specimens, 1 of them from an urban area of Barra do Garças. The new record of P. diasi is important for the understanding of the epidemiology of Chagas disease, mainly because this species is found naturally infected with Trypanosoma cruzi (Chagas, 1909). Studies on the ecology, biogeography, and vector–host/parasite interactions of P. diasi are essential.