Twenty one species of lizards (four families) were found in the region of Balbina Hydroelectric Station, Uatumã river, 60 km east of Presidente Figueiredo, Amazonas State, Brazil. Most lizards are exclusive forest dwellers exploring horizontal, vertical, or both spaces. Twenty species are diurnal and one is nocturnal; no marked seasonal difference in activity was observed. Except for the known food specialistsIguana iguana(leaves) andPlica umbra(ants), and the omnivorousTupinambis nigropunctatus, all other species seem to be arthropod generalists. Three guilds with widely overlapping resource utilization are evident. These patterns are very similar to those found in other localities in the Amazon Basin, probably because of the similarity among their herpetofaunas and structural habitats. A brief review of the hypothesis that tries to explain how the members of these complex assemblages coexist shows that, although some authors suggest that competition is weak or inexists in these assemblages, there is no published study demonstrating the role of competition and/or predation in an Amazonian lizard community.