Urania sloanus is an endemic species in Jamaica. The species probably became extinct at the end of the 19^th century or the beginning of the 20^th century. During the work on combining the collections of exotic butterflies in the Upper Silesian Museum in Bytom, one specimen of this taxon was found. The discovery of this species in the Museum of Upper Silesia in Bytom led us to search for entomological collections in other Polish museums. As a result of our search, we found three additional specimens: two specimens in the collection of the Museum of Natural History of the University of Wrocław and one at the Zoological Museum of the Polish Academy of Sciences in Warsaw. In total, in the Polish museum collections, the species was represented by four specimens. In our publication, we also paid attention to the role of museum collections as important repositories of biodiversity in the context of the development of modern methods in the field of molecular genetics, as an important source of genetic information.