Upper montane oak forests in the Cordillera de Talamanca show a high diversity of bryophyte species and great diversification of microhabitats. A complete bryophyte inventory of six hectare of forest yielded 206 species: 100 mosses, 105 hepatics, and one hornwort. Based on similarities in species composition the forest microhabitats cluster into three main groups: 1) forest floor habitats (including tree base), 2) phyllosphere, and 3) other epiphytic habitats. The contribution of forest floor habitats to total bryophyte species richness is much higher than in forests of lower elevational belts. Distribution of species and life forms in different microhabitats reflect the vertical variation of humidity and light regimes. At the same time they show the impact of the pronounced dry season and the structural characters (tree height, stratification, number of host tree species) of these oak forests on epiphytic bryophytes compared to more humid forests and upper montane forests of lower stature.