This paper deals wlth the cycle of cytogenetical researches on the Triatominae ("Kissing bugs") since 1948. It has been described the caryotypes and the problems of the multiple sex chromosomes, the existence in some species of the heteropycnosis of some autosomes and considered its significance in isolating mechanism in evolution. The chronology of the synthesis of DNA along the stages in the testicular tubes has been analyzed by autoradiography and cytometry. The significance of the differences in the number and relative sizes of the testicular tubules has been analyzed as taxonomic character. Part of these researches has been dedicated to the cytogenetic study of the male sterility of the interspecific hybrids.