leucism is an inherited disorder, characterized by the lack of pigments in part or all of the body, normal coloration of the eyes and, in birds, in naked parts such as the bill and legs. this kind of disorder is sometimes erroneously designated as albinism or partial albinism. in this study, we present a case of leucism in a wild owl. the studied individual presented completely white plumage, light-yellow coloration of legs and bill and normal coloration of eyes. according to morphological features, this owl is a specimen of burrowing owl, athene cunicularia (molina, 1782). to confirm the species identity, we used cytogenetic analyses for karyotypic determination, comparing it to the previously described one in the literature. we also studied a captive female of a. cunicularia to complement the species karyotype, which was described in the literature based only on a single male. the karyotype of the leucistic owl individual was compatible with the previously published one for a. cunicularia, confirming the bird was a male specimen. cytogenetic analysis of the captive female showed that the w sex chromosome is metacentric and comparable to the seventh pair in size. this is the first description of a case of leucism in a. cunicularia for south america. long-term studies are needed in the neotropical region to evaluate survival and breeding success in leucistic birds.