The easternmost part of Amazonia, east of the Tocantins River, in Brazil, is also known as the Belém Area of Endemism (BAE) and falls mostly within the Amazonian “arc of deforestation” with the highest rate of deforestation in the region. Even though only one reptile species may be strictly endemic to the BAE, according to present knowledge, recognition of this area is useful for conservation purposes. Herein, we present a revision of current knowledge on the diversity and distribution of Squamata in the BAE in order to support conservation strategies and detect the main sampling gaps. We searched the literature and databases of several herpetological collections to compose the list of species for the area. For each species, we recorded distribution, habitat, and microhabitat. We present species accumulation curves for the whole area and for the two municipalities with largest samples, and prepared maps with species richness per municipality, current vegetation coverage, and conservation units present in the region. Additionally, we compare the number of known forest species of Squamata with the proportion of current forest cover for the best-sampled municipalities to test if there is a relationship between the conservation state of the area and the number of species. Our sampling reports 23,598 records of 147 species, including 7 amphisbaenians, 39 lizards, and 101 snakes. Sixty species (40.8%) are restricted to Amazonia, 12 (8.2%) are shared only with the Cerrado and 19 (12.9%) only with the Atlantic Forest, 1 (0.7%) is introduced, and the remaining 55 (37.4%) are shared with other biomes. Amphisbaena anomala and Stenocercus dumerilii are mostly associated with the BAE, and Atractus hoogmoedi is only known from its type locality and might represent a BAE endemic. Two species are threatened at the national level (Brazilian Red List) and five at the state level (Pará Red List). The largest samples and species richness are from the municipalities of Belém and Viseu; 9% of the municipalities have > 50 species, 32.4% have 1–10 species, and 38% remain unsampled. For 38 of the 50 municipalities with < 10% of forest cover, we have virtually no information on forest-dwelling species. Despite its high rate of deforestation, our knowledge of the herpetofauna of the BAE is based on a few limited areas; this fact hinders analyses of correlation with environmental factors and more appropriate definitions of conservation strategies. The largest tracks of forest remnants are mostly in indigenous lands, so it is important to develop strategies for studying these areas. The historically dynamic nature of the interchange between Amazonia and Cerrado biomes in the BAE might explain the tolerance of the species presented here to disturbed and secondary forests. Nonetheless, the increasing expansion of pastures, monocultures and urban areas in the area represent real and alarming threat.