The liverwort Crossocalyx hellerianus is a rare and threatened epixylic species associated with primeval forests. Until 2020, a total of 11 localities of this plant had been recorded in the entire Tatra Mountains, including 4 in the Polish part and 7 in the Slovak part. This paper presents the results of studies conducted between 2012 and 2025 across the whole Tatra massif. Eleven forest complexes in the Polish High and Western Tatras were selected and subjected to detailed inventory surveys during 2024–2025. A total of 86 localities of Crossocalyx hellerianus were recorded, including 67 in the Polish part of the massif and 19 in the Slovak part. The publication presents 68 new localities of the species. The species occurs most frequently within the altitudinal belt of 1201–1300 m a.s.l., and its largest population is located on Szczoty Wołoszyńskie (High Tatras, Roztoka Valley). It reproduces mainly vegetatively, although a small number of fertile specimens are constantly present. An important observation is the occurrence of Crossocalyx hellerianus (as well as other relict liverwort species) not only in old-growth forests rich in diverse microhabitats, but also in regenerating forest stages (the so-called rowan thickets) containing decaying wood remaining from the previous stand collapse.