Laughing Falcons (Herpetotheres cachinnans) are common, medium-sized falconids that occur throughout the Neotropical region and marginally in the Nearctic American continent. There is little data on their breeding biology with the only information available based on scattered records. Here, we report data on 11 nests of H. cachinnans from the Pantanal, Brazil, including four in nest-boxes, between 2007–2008. The breeding season occurred between July–December, which is in accordance with the few records for this region. Records of two eggs or nestlings were found in 28% (n = 3) of nests, while the remaining 72% (n = 8) had one egg or nestling. The eggs were rounded and buff with brown markings or dark brown or purplish brown with darker markings. The hatchlings, even when a few days old, are pale buff overall in plumage with the distinctive black mask, typical of the adults. An undescribed vocalization of the nestling was recorded, which is similar to an uncommon vocal type emitted by the adults when disturbed. The study reveals novel data on the use of nest-boxes and on the breeding biology of the species, and reinforces the importance of such studies on its conservation.