The causes of neonatal hypoxemia are usually either pulmonary or cardiac pathologies. We report a case of a 2-month-old boy with oxygen dependency since birth. He would desaturate down to 88-90% whenever supplemental oxygen was weaned off. Initial screening echocardiograms described only a small atrial septal defect, thus lung disease was thought to be the aetiology. Eventually, a detailed echocardiogram and CT angiography revealed anomalous right superior vena cava (RSVC) draining into the left atrium (LA). Echocardiography with bubble study injected via the upper extremities showed brisk filling of “bubbles” in the left heart, confirming fixed right-to-left shunting. Anomalous RSVC drainage into the LA is an extremely rare form of anomalous systemic venous drainage whereby unexplained hypoxemia is present and is sometimes the only clinical manifestation. Surgical correction of this anomaly is indicated to prevent complications of cyanosis and risk of systemic embolization. The surgery generally carries low risk and is associated with good long-term prognosis.