A study of the butterfly fauna of the Croatian island of Korčula is presented. Fieldwork was carried out from 2011 to 2017, during several visits in different vegetation seasons, from the end of April until November. Altogether, 53 species were recorded during the survey, including 21 new records for the island. Along with literature records, 60 butterfly species have so far been recorded on Korčula. When compared with other Adriatic islands, only Cres, Lošinj, Krk and Brač have more butterfly species than Korčula. In general, the number of species, as well as species abundance, was very high in most localities, indicating the long-term persistence of suitable habitats on the island. Records of rare species such as Iolana iolas, Cupido minimus, Aglais urticae, Satyrus ferula and Pyrgus armoricanus present important extensions of their known ranges on the islands and in Dalmatia.