A total of 326 species of amphibians and reptiles are known from Guatemala and Belize and adjacent marine waters; this number represents 112 species of amphibians, 207 species of terrestrial or freshwater reptiles, and seven species of marine reptiles (six turtles and one snake). Eight herpetofaunal areas are recognized on the basis of the distributions of non-marine species. A description of these areas is provided with a listing of all species known to inhabit each area. The number of species in major taxonomic groups living in different faunal areas and the proportion of the total herpetofauna in an area comprised by taxonomic group are analyzed. Comparisons of the shared and total number of species of amphibians and reptiles between areas are made and similarity coefficients are subjected to cluster analysis. The number of amphibians species remains about constant at elevations between 0 m and 1,500 m; above this level the number steadily decreases. The number of reptiles, on the other hand, decreases steadily from 0 m to 4,000 m, the number of species decreasing with increasing elevation proportionally much more rapidly than in amphibians. An increase in number of amphibians and reptiles occurs between 1,200 m and 1,700 m; this increase may be the result of overlapping of the vertical distributions of lowland- and highland-adapted species, it may be a reﬂection of the relatively high number of endemic species restricted to moderate elevations, or it may be owing to a more diverse habitat found at these elevations. The herpetofauna of Guatemala is still poorly known. Some of the regions meriting intensive ﬁeld investigations are the Sierra de los Cuchumatanes, Sierra de Merendén, and the Sierra de Chuacus.