Pericardial cysts are infrequent benign intrathoracic lesions. They rarely cause symptoms, and they are usually discovered on routine X-ray by chance. Over 70% of the cases occur at the right anterior cardiophrenic angle. Surgery is generally not indicated if the diagnosis of pericardial cyst can be made with certainty, and then an operation is performed to rule out other lesions. The authors present 3 cases of pericardial cyst confirmed by surgery. In two Gases Of the three, the pericardial cysts were located at the right anterior cardiophrenic angle, and in one case, at the left superior area of the posterior mediastinum. We managed them successfully by surgery, and they were discharged uneventfully. [KTCS 1983;1:167-170]