Polybrominated diphenyl ethers (PBDEs) are used as flame retardants in several products, although they can act as neurotoxic, hepatotoxic and endocrine disruptors in organisms. In Brazil, their levels in aquatic sediments are poorly known; thus, concerns about the degree of exposure of the Brazilian population to PBDEs have grown. This study aimed to quantify the presence of PBDEs in sediment samples from an important groundwater water supply in Ribeirao Preto, Brazil, and to contribute to studies related to the presence of PBDEs in Brazilian environments. Gas chromatography coupled with Electron Capture Detection (GC-ECD) was used for quantification after submitting the samples to ultrasound-assisted extraction and clean-up steps. Results showed the presence of six PBDE, BDE-47 being the most prevalent in the samples, indicating a major contamination of the penta-PBDE commercial mixture. The concentration of ΣPBDEs (including BDE-28, -47, -66, -85, -99, -100, -138, -153, -154 and -209) varied between nd (not detected) to 5.4 ± 0.2 ng g−1. Although preliminary, our data show the anthropic contamination of a direct recharge area of the Aquifer Guarani by persistent and banned substances.