Carbonic anhydrases (CAs) are metalloenzymes that catalyze the interconversion of carbon dioxide (CO2) and hydrogen carbonate. CAs are distributed over all the three domains of life and are divided into five distinct evolutionarily unrelated gene families (alpha, beta, gamma, delta, zeta). In the large fungal kingdom, the majority of fungi encode multiple copies of beta-CAs, with some also possessing genes for alpha-class CAs. Hemiascomycetous and basidiomycetous yeasts encode one or two beta-CAs, while most of the filamentous ascomycetes have multiple copies of genes encoding alpha- and beta-CAs. The functions of fungal beta-CAs have been investigated intensively, while the role of fungal alpha-CAs is mostly unknown. The beta-CAs are involved in sexual development, CO2-sensing, pathogenicity, and survival in ambient air. Only recently, researchers have begun to use functional and structural data of CAs from pathogenic and non-pathogenic organisms to develop powerful and effective drugs and inhibitors or to identify enzymes that can be utilized in industrial applications. Despite the large number of fungal CAs known, only five have been characterized structurally: the alpha-CA AoCA of Aspergillus oryzae, the full length beta-CA Can2 from the pathogenic basidiomycete Cryptococcus neoformans, the N-terminally truncated Saccharomyces cerevisiae beta-CA Nce103, and two beta-CAs of Sordaria macrospora. This review focuses on the functional and structural properties of fungal CAs.