Kaniv Nature Reserve is a unique area in the middle part of the Dnieper river. The total area of the reserve is 20.27 square km. It includes hills, the Zmiini islands and Shelestiv island. About 1500 species of fungi are known in the reserve (Lavitska, 1947; Kryshtal, 1947; Raevska & Komaretska, 1949; Zerova, 1950-1978; Dudka, 1962; Solomakhina, 1971-1996). During many years of study (from 1948) of fungi in the reserve, some changes have become apparent. Certain species which were observed frequently before, for example, Boletus satanas, are absent now. At the same time, Coprinus pomaceus was first recorded only in 1989. As a result of radio-pollution of the area after the Chernobyl disaster the development of some parasitic fungi (e.g. Rhytisma acerinum, Rhytisma punctatum) has been inhibited. Another discovery was the connexion between a fungus and its host plant resulting in simultaneous maturity of fungal fruitbodies and plant seeds (Puccinia komarovii on Impatiens parviflora). In some epigeous larger fungi (e.g. Hydnum repandum) a sporadic occurrence of fruitbodies has been observed, even in favourable conditions, perhaps because the mycelium is resting. There are also species which are common every year, apparently independent of conditions (e.g. species of Xylaria, Hypoxylon, Hirneola, Crepidotus and Marasmius). Five species of fungi listed in the Red-Data Book have been found in the reserve: Hirneola umbellata in particular is protected in the Kaniv region adjacent to the Dniper river. These long-term observations of fungal diversity in the reserve should be continued yearly, in every season.