This study aimed to identify the tabanid species as well as their relative abundance and seasonality in the sub region of Miranda, a transition area from the Pantanal to the highland savanna (Cerrado). Tabanids were most abundant during the rainy seasons and population peaks were observed in October 2001, February/March and December 2002, generally associated with the beginning of the rainy season (October 2001 and December 2002) and temperature increasing. Trypanosoma vivax (Trypanosomatidae) is a pathogenic trypanosome found in wild and domestic herbivores, mainly in cattle (Bos taurus, Bos indicus, and crossbreeds), in Africa and South America. Although in the African continent T. vivax is cyclically transmitted by tsetse flies (Diptera: Glossinidae), it is only mechanically transmitted by tabanids (Diptera: Tabanidae) in South America. Indeed, the role of tabanids as mechanical vectors of T. vivax should be considered important also in Africa, since transmission by an African species has been demonstrated (Desquesnes & Dia, 2003). The epidemiology of cattle trypanosomiasis in the Pantanal, which is widely spread in the region (Silva et al., 1996), is considered to be tabanid dependent. The Pantanal is composed by several sub regions and except for the studies conducted at the Nhecolândia sub region (Barros & Foil, 1999; Barros, 2001), tabanids from other areas are poorly known or virtually unknown. This study aimed to identify the tabanid species as well as their relative abundance and seasonality in the sub region of Miranda, a transition area from the Pantanal to the highland savanna (Cerrado).