Demographic studies on crocodilians in subject to strong human disturbance habitats are scarce, particularly in the Neotropical Region. This work provides the first survey data of abundance and population size structure of a neotropical caiman, Caiman latirostris, in disturbed habitats of northwestern Uruguay (30°S, 57°W). We conducted nocturnal surveys in agriculture impoundments (2–116 ha) of the Ñaquiñá and Lenguazo stream basins during summer, from 2001 to 2004. About 81% of impoundments were inhabited by caiman, with relative abundance indices between 2.1 and 4.4 × km⁻¹. Population size structure in the study area was similar throughout the study period; sub-adults from 50 to 119 cm of total length were the most abundant (57–78%), followed by adults (25–33%), and juveniles (6–22%). Relative abundance indices suggested that C. latirostris is not seriously endangered in contrast to previous local reports. The construction of agriculture impoundments in northwestern Uruguay for irrigation of rice and sugar cane seem to have been favored C. latirostris, as indicated by population size structure.