Morphological description of the male genital organs of Pontoporia blainvillei (Gervais & d’Orbigny, 1844)

or Franciscana is a small cetacean endemic of South Atlantic Ocean and its highlighted as the most endangered species. Despite the necessity to development conservation strategies for studies aiming to feature the reproductive biology and morphological characteristics of the genital organs are still scarce. In this context, the aim of this study was describe the morphological aspects of the genital organs of . For this purpose, six male specimens of stranded on the southeast region of Brazil, were used. Initially animals were measured, and the genital organs were collected, dissected and photodocumented. Then, fragments of all collected organs were submitted to microscopic analysis. The male genital organs of showed similar results described for other cetaceans, such as, topography in abdominal cavity, presence of two testicles with epididymis, fibroelastic penis with sigmoid shape and presence of deferent duct. Moreover, a male uterus non-functional, two vestigial bones that support the penis, one retractor penis muscle and presence of associated muscles that support the entire reproductive apparatus were observed. However, some differences were present, such as, a simple cubic epithelium in the light of the epididymis, a small testicle even in sexually mature animals and absence of prostate, not previously observed in other cetaceans. Therefore, the animals analyzed showed similar features to other cetaceans, however some peculiarities were observed.