The approach to the analysis of the fauna composition and completeness of its detection through the concept of “species discovery curve” is considered. Beetles of the family Cryptophagidae were taken as a model group. The dynamics of the accumulation of the information about the composition and volume of the Cryptophagidae fauna of the Ukrainian Carpathians during the eight stages of their study (the middle XIX, late XIX and the end of XIX century, the beginning of the XX century, the period until 1930–1940; middle and second half of XX century, and the current state for 1999 and 2021) are presented. In general, the composition of the cryptophagid fauna in the Ukrainian Carpathians is estimated at 116 species. This is 16 % more compared to what was known 100 years ago, i.e. each stage of the study adds about 5 % to the known species richness of this group of beetles. The components of fauna changes are analysed separately: 1) due to the changes in the nomenclature of existing species, 2) as a result of finding rare species (i.e. strengthening research efforts), 3) due to division or vice versa – combining existing species into two or three “small” species that were previously considered as morphs, varieties, or were not distinguished.