To evaluate the changes in arterial oxygenation after portal decompression in Budd-Chiari syndrome (BCS) patients with hepatopulmonary syndrome (HPS). From June 2014 to June 2015, all patients with BCS who underwent balloon angioplasty or transjugular intrahepatic portosystemic shunt (TIPS) creation at our institution were eligible for inclusion in this study. Arterial blood gas analysis was performed with the patient in an upright position and breathing room air at 2-3 days and 1 and 3 months after the procedure. Eleven patients with HPS and 14 patients without HPS were included in this study. The procedure was technically successful in 24 patients. One patient with HPS had technically unsuccessful TIPS creation. Reobstruction or TIPS dysfunction was not detected in any patient within 3 months after the procedure. For patients with HPS, the alveolar-arterial oxygen gradient (A-aO2) remained comparable to baseline 2-3 days after the procedure (-3.2 ± 11.9 mmHg; p = .412), significantly improved 1 month after the procedure (-11.7 ± 6.4 mmHg; p < .001), and then returned to baseline 3 months after the procedure (-1.3 ± 12.5 mmHg; p = .757). For patients without HPS, the A-aO2 remained comparable to baseline at all three time points after the procedure (+1.4 ± 8.3 mmHg, +3.5 ± 8.1 mmHg, and +1.3 ± 8.2 mmHg; p = .543, p = .137, and p = .565). Arterial oxygenation transiently improves after portal decompression in BCS patients with HPS. • Intrapulmonary vascular dilation and hepatopulmonary syndrome are common in patients with Budd-Chiari syndrome. • Arterial oxygenation transiently improves after portal decompression in Budd-Chiari syndrome patients with hepatopulmonary syndrome.