Arteriovenous malformations (AVMs) are vascular anomalies characterised by arteriovenous shunting with the lack of a capillary bed. Since the veins that drain an AVM contain arterialised blood, they would be expected to have a higher venous oxygen saturation (SvO2) than normal veins. Due to the paramagnetic properties of deoxyhaemoglobin, SvO2 can be calculated using magnetic susceptibility mapping (SM). Here, we calculated SM-based SvO2 in five patients with a brain AVM. We found higher SvO2 in the AVM draining veins compared to normal veins, showing that SM might be a valuable tool to study AVM physiology.