The author studied the anatomy of the dorsal vessel and aorta of Triatoma infestans, reared during some years in the laboratory. The principal result is the observation that, instead of three pairs of ostioles, the heart has only one opening in each of the three chambers of the heart. In material collected in the field (Panstrongylus megistrus) we found normally three pairs of ostioles, but with certain differences in size and localization.