Chironomidae is a cosmopolitan family of dipteran insects occurring in all zoogeographical regions of the world. The family is quite diverse and the objective of this study was to examine diversity of chironomid larvae in 115 wetlands in an extensive area of Neotropical region (∼220,000 km², southern Brazil) by analysis of richness and composition in different wetland subsystems, types and classes. Also examined were effects of wetland area, altitude, water conductivity and nutrients on these community descriptors. A total of 36 genera was found, with Chironominae showing the greatest richness, followed by Tanypodinae and Orthocladiinae. The richness and composition changed between wetland subsystems, types and classes. However, no single parameter strongly influenced the chironomid richness and composition in this broad spatial scale survey. The broad spatial scale and details of this study make it an important contribution to knowledge of chironomid diversity in the Neotropical region.