Gymnomitrion adustum has been erroneously reported from Slovakia and Poland on several occasions. These data were published between 1865 and 1961 for the Tatra Mountains (Western Carpathians) area. Gymnomitrion adustum was mistaken for Gymnomitrion brevissimum and some species of the genus Marsupella, such as M. sprucei, M. funckii and M. condensata. This paper presents the first records of Gymnomitrion adustum in 23 localities in the Tatra Mts (20 from Slovakia and 3 from Poland), as well as characteristics of the diagnostic features of this species. In most of the European countries where G. adustum has been recorded, this liverwort is included in red lists of endangered species; this is a rare species in the Slovakian Tatra Mts, and it is very rare in the Polish Tatra Mts.