A comparative study of the altitudinal distribution of bryophytes and vascular plants on littoral Dinarides was conducted along two complete, about 1500 m long elevational transects in Gorski Kotar and Sjeverni Velebit. A total of 570 plant taxa were recorded, of which 185 bryophyte species, which makes one fourth of known bryophyte diversity in Croatia. Both groups show similar patterns of alpha diversity, best described by the cubic regression function with diversity maxima approximately between 1100 and 1200 m a.s.l. The total number of taxa of vascular plants and bryophytes is the lowest in the lowest belt of holm oak, and the highest in the complex of spruce communities. High number of taxa and intra-belt beta diversity of the vascular flora in the belts of oriental hornbeam and European hop-hornbeam is a result of the long-lasting intensive degradation of these forests, which has enabled the establishment of a large number of non-forest taxa. Vascular plants exhibit the highest species turnover on the border of two phytogeographical regions, while the most prominent species turnover of bryophytes appears with evergreen boreal and subalpine vegetation types. Bryophytes exhibit wider altitudinal ranges and a greater tendency toward exclusively higher elevations compared to vascular plants. Neither vascular plants nor bryophytes follow Rapoport’s rule of increment of the average altitudinal range of species with increasing elevation. The analysis of floristic similarity confirmed the existence of eight discrete altitudinal forest belts in the littoral Dinarides and a clear floristic division between the Mediterranean region in the lower and the Euro-Siberian-North American phytogeographical regions at higher altitudes. Forest vegetation is ecologically primarily defined by climatic gradients of mean annual temperature and precipitation, and gradients of substrate characteristics (pH reaction and amount of calcium chloride, the amount of organic matter and litter cover). The indicator values for bryophytes exhibit weaker indicator potential in explaining floristic composition compared to indicator values for vascular plants, which proves that these two groups only partially describe the same ecological gradients.