The Neotropical lizard Tropidurus torquatus (Wied, 1820) is a generalist of habitats and habits, occurring both in preserved and in disturbed environments, including urban areas. In the present study, we analyzed the diet composition of populations of T. torquatus from two areas in the state of Rio de Janeiro in southeast Brazil: one with relatively little impact (Bravo 10, in Ilha da Marambaia) and one highly modified by anthropic influence (Rio de Janeiro Botanical Gardens). A total of 55 sexually mature lizards was collected (29 in the Botanical Gardens and 26 in Marambaia). We also sampled invertebrates on the ground and on vegetation to estimate the local potential availability of prey. Both populations presented relatively diverse diets, with ants and winged Hymenoptera (non-ant) being the predominant food items in the Botanical Gardens, whereas in Marambaia ants predominated, though termites were more representative in numerical terms (despite the low frequency of occurrence). In both areas, the proportion of plant material in the diet (10.6% of the total volume in the Botanical Gardens and 9.5% in Marambaia) was relatively low compared with other conspecific populations. Differences in diet between the two lizard populations were not significant, though the diets differed from the estimated local supply of prey in both areas. Our results suggest that the differences in the degree of anthropic disturbance between the two environments are not reflected in the diets of the lizards or in the availability of potential prey, with little variation between areas in both cases.