OBJECTIVE: We retrospectively evaluated the effect of transpulmonary radiofrequency ablation (RFA) of liver tumours on the lung. METHODS: 16 patients (10 males and 6 females; mean age, 65.2 years) with 16 liver tumours (mean diameter 1.5 cm) underwent transpulmonary RFA under CT fluoroscopic guidance. The tumours were either hepatocellular carcinoma (n=14) or liver metastasis (n=12). All 16 liver tumours were undetectable with ultrasonography. The pulmonary function values at 3 months after transpulmonary RFA were compared with baseline (i.e. values before RFA). RESULTS: In 8 of 16 sessions, minor pulmonary complications occurred, including small pneumothorax (n=8) and small pleural effusion (n=1). In two sessions, major pulmonary complications occurred, including pneumothorax requiring a chest tube (n=2). These chest tubes were removed at 4 and 6 days, and these patients were discharged 7 and 10 days after RFA, respectively, without any sequelae. The pulmonary function values we evaluated were forced expiratory volume in 1 s (FEV1.0) and vital capacity (VC). The mean values of FEV1.0 before and 3 months after RFA were 2.55 l and 2.59 l, respectively; the mean values of VC before and 3 months after RFA were 3.20 l and 3.27 l, respectively. These pulmonary values did not show any significant worsening (p=0.393 and 0.255 for FEV1.0 and VC, respectively). CONCLUSION: There was no significant lung injury causing a fatal or intractable complication after transpulmonary RFA of liver tumours.