Computed tomography of five cases of thymic carcinoma was reviewed. The subtypes of thymic carcinoma were squamous (two cases), lymphoepithelioma-like (one case), undifferentiated (one case), and basaloid (one case). The patients ranged from 52 to 72 years of age. Computed tomography showed anterior mediastinal tumors infiltrating along the pleura or mediastinum with frequent internal necrosis or calcifications. The three nonsquamous cell cases developed extrathymic metastases to the mediastinal lymph nodes, lung, or chest wall. Although the CT features of thymic carcinomas were similar to those of invasive thymoma, the former showed more aggressive behavior. Among the four variants of thymic carcinoma, squamous carcinomas were less aggressive and had less tendency to develop necrosis than the others.