A 54-year-old asymptomatic man underwent a video-assisted thoracoscopic left pneumonectomy for squamous-cell carcinoma. During the surgery, a complete left pericardial defect was unexpectedly discovered, but no special intervention was made. The preoperative chest CT was reciewed, which showed the heart extended unusually to the left, but the left pericardial defect was not evident. The operation time was 204 min and the patient was discharged from hospital upon recovery 9 days after the surgery. The pathological result indicated moderately differentiated squamous-cell carcinoma (T2N1M0, stage ⅡB), and metastasis was found in the parabronchial lymph nodes (3/5). The patient did not receive chemotherapy after the surgery, and there was no signs of recurrence 6 months after the surgery. Complete pericardial defects usually do not endanger the lives of patients, and if the patient is asymptomatic, pneumonectomy is feasible.