Abstract.We herein investigate the case of a patient with a tuberculous diaphragmatic abscess confirmed by pathology. The patient underwent plain computed tomography (CT) examination of the chest and contrast-enhanced abdominal CT examination. The abscess appeared as hypodense mass with thick and irregular wall, which was enhanced on the contrast-enhanced CT images. The shape of the mass resembled an irregular double convex lens. No enlarged lymph nodes were detected on the CT images. The presence of a tuberculous diaphragmatic abscess should be suspected in patients with a diaphragmatic hypodense mass with enhanced thick walls, even when there is absence of enlarged lymph nodes on the CT images.