Thymic cysts are rarerly encountered lesions which, are only 1 to 2% of all mediastinal masses. We present six patients with thymic cysts diagnosed between 2000 and 2004 in this report. There were three male and three female patients whose ages ranged from 34 to 64 years (mean age, 46 years). Four patients are nonsmoker. None of the patients had a previous history of an etiologic factor such as trauma, surgical procedure or evidence of significant inflammation. While one patient was asymptomatic, there were chest pain in three patients, cough in two patients, hemoptysis in two patients and dyspnea in one patient. Thymic cyst was located in anterior mediastinum in five patients and in upper mediastinum in one patient. Cysts were resected with thoracotomy in four cases and with sternotomy in two cases. Their size ranged from 5 to 9 cm in diameter. In pathologic examination, two cysts were multilocular. In conclusion, thymic cysts are rare masses. Differential diagnosis of mediastinal masses, especially anterior mediastinal masses should be included thymic cysts.