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5d transition metal oxides provide a fertile playground to explore new phenomena resulting from the interplay between topology, spin-orbit, and electron-electron correlations. To date, however, limited studies of topological properties exist due to the difficulty in synthesizing single crystals of these oxides. Here, I will present magnetotransport and quantum oscillations study on high-quality single crystals of Dirac semimetallic oxide BiRe₂O₆. It crystallizes in a monoclinic structure with space group C2/c (SG#15) and is a Pauli paramagnetic. Intriguingly, it exhibits large positive magnetoresistance of 110³ % at 2 K. Unlike other topological semimetals that show large MR, it evidences high electron carrier density and mobility of 0.510²² cm⁻³ and 110³ cm² V^-1 s^-1, respectively. Moreover, analysis of de Haas–van Alphen oscillation measurements and band structure calculations reveals the Fermi surface comprising of multiple pockets with small effective masses. Our findings may trigger to study of novel phenomena of correlated Dirac electrons in topological materials based on oxides.