Resumo. Odonata sampling effort in the state of Minas Gerais has intensified throughout the 21st century. However, research on these insects in some regions and ecosystems such as the Deciduous Forest are incipient, and the effect of prolonged dry periods over these insects is still unknown. This study thus aimed to assess changes in adult Odonata species composition over one year in a Brazilian Deciduous Forest and the Odonata species richness in the Mata Seca State Park in the Manga and Itacarambi municipalities in the Northern region of the state of Minas Gerais State, Brazil. Twenty-four days of sampling were distributed in February, May, July and November, adopting an active search through entomological nets close to lentic environments (Lagoa Angical, Lagoa Comprida, Lagoa Encantada, Lagoa da Prata and two wetlands of Lajedo da Lua); lotic environments (São Francisco river) and in associated terrestrial ecosystems. In total, 55 species were collected. Rainy and dry periods altered Odonata communities’ composition but did not affect species richness and abundance due to the presence of permanent lagoons associated with the São Francisco river. This study shows the importance of the Mata Seca State Park for preserving Odonatofauna in the state of Minas Gerais and for protecting those permanent lagoons.