We studied the reproductive biology of a population of Blue-fronted Amazons (Amazona aestiva) in the Pantanal of Mato Grosso do Sul State, Brazil, between 1997 and 1999. Nesting occurred from August to December. We monitored 94 nests which were found in trees of different sizes. Nesting trees were distributed in all major vegetation associations (floodplains, grasslands, scrub savanna, savanna, arboreal savanna, riparian forests, and pastures). We found about half of nests (53%) in an open and disturbed area of 34 km², yielding a density of 0.5 nests/km². In the remaining 486 km² of the study area, we estimated a mean density of 0.03 nests/km². This could reflect preferences towards open and anthropic-influenced habitats or simply visibility bias. We found most of the nests in Palmae, Leguminosae, and Bignoniaceae, but the proportion of successful nests did not differ between tree types. Average clutch size varied little among the three years of study, but nest survival and the proportion of fledglings per female were lower in 1998 than in 1997 and 1999. The cause of the lower fledging success in 1998 was not determined, but deforestation, an early onset of the rainy season, and higher rates of nest visitation by researchers may have been involved.