A 68 year-old man presented with dyspnoea and chest pain. Computed tomography showed a massive bilateral pulmonary embolism. A 7.5 French pulmonary artery catheter (PAC) was inserted from the right internal jugular vein, and placed at the main pulmonary artery (PA) due to a thrombus in the distal PA. Continuous heparin sodium and urokinase infusions (240,000units/day) were started. The PA pressure decreased gradually to within the normal range after two days. Three days after insertion, the PA waveform suddenly changed, he subsequently complained of chest pain, and the blood pressure rapidly decreased. Echocardiography demonstrated marked pericardial effusion. Computed tomography showed right ventricular perforation by the catheter, and contrast dye injection from the catheter tip demonstrated pericardial space enhancement. A median sternotomy was performed, and the perforation was detected in the anterior right ventricular wall. Direct buttress suture was placed, and the catheter was removed. He was subsequently discharged without any further complications. We encountered a rare case of postoperative RV perforation caused by a PAC. It is important to keep in mind that such a complication could arise not only during but also a few days after PAC insertion.