(Uploaded by Plazi for the Bat Literature Project) This study is a summary of the present knowledge on the existence and distribution of the bat species occurring in the State of Paraná, Brazil, identifying areas for additional surveys. The analysed data was obtained from the collection belonging to the Capão da Imbuia Natural History Museum (Museu de História Natural Capão da Imbuia, MHNCI) in Curitiba, and from a bibliographical update. Fiftythree species in 5 families were identified the Phyllostomidae present the highest abundance of species (25; 47% in total) followed by the Molossidae (13; 24%), Vespertilionidae (12; 23%), Noctilionidae (2; 4%), and Emballonuridae (1; 2%). The results indicate that only 55% of the species belong to the Biome of the Atlantic Forest and that there is a relative predominance of vespertilionids and molossids over phyllostomids. These results reveal an impoverished fauna confirming the subtropical character of the Paraná region. The distribution of the species is irregular. Significant differences occur between the species compositions in the three principal forest formations of Paraná. The Semideciduous seazonal Forest contains the highest abundance (39; 74%) and the highest number of exclusive species (10). It is followed by the Mixed Ombrophylous Forest or Araucaria Forest (36; 68%), with 6 exclusive species, and finally by the Dense Ombrophylous Forest (= Atlantic Forest sensu stricto) with 33 species (62%) of which only 3 are exclusive. The degree of knowledge was estimated with the Method of Squares. The area was subdivided using a grid drawn at intervals of 30' longitude and 30' latitude, forming 93 small squares. Of these, 53% (49 small squares) do not contain any bats and the average per square is 3.4 species, much less than the 24 species that would be considered satisfactory for Paraná. Only three small squares reach this amount: two surveys done in the eastern (Curitiba) and one in the northern (Londrina) regions. Approximately two-third of the territory of Paraná can be considered poorly explored and must be classified as areas requiring additional surveys, since only 11 bat species have been identified so far.