<p>Aquatic beetles are insects with morphological and behavioral adaptations for aquatic life. They have potential as bioindicators and in ecological and evolutionary studies; however, they remain understudied in tropical regions such as the Cerrado (Neotropical savanna), a biome that has been increasingly degraded and has two well-defined climatic seasons. In environments that have well-defined climatic seasons, the influence of the different seasons on structure and functioning must also be considered when thinking about the management of these ecosystems. This study aims to evaluate the effect of seasonality on the diversity of aquatic beetles in the Brazilian Cerrado. We collected larvae and adults of water beetles in five streams during the rainy and dry seasons. We measured environmental variables and calculated diversity metrics for both seasons and life stages. Our main findings show that the richness of larvae and adults of aquatic beetles did not differ between seasons, while the abundance of larvae was higher in the rainy season. The species composition of larvae and adults differed between seasons. The main differences in functional diversity were found for larvae and different environmental parameters influenced the diversity of these organisms, such as dissolved oxygen, water temperature, conductivity, and pH. These results show that seasonality-related environmental variables drive the diversity of aquatic beetles, which seems to be able to maintain their ecosystem functions regardless of the season, probably due to the diversity of habits, behaviors and life cycles of the different families that occur in this group.</p>