Emphysematous pyelonephritis (EPN) is a severe gas-forming infection of the renal parenchyma and surrounding tissues. Patients with EPN commonly present with high fever, chills, and flank pain. These symptoms mimic a simple urinary tract infection, such that diagnosis is often delayed. Because of its life-threatening fulminant course, the early detection of EPN and its prompt treatment with intravenous antibiotics with or without percutaneous drainage are critical. Here we describe a case of a 63-year-old Korean female with diabetes mellitus who had no specific symptoms or signs of EPN. A chest computed tomography (CT) scan to assess a right pleural effusion incidentally detected an abnormal gas shadow in the renal parenchyma. An abdominal CT scan performed 5 days later showed increased gas within the kidney parenchyma, but the patient still had no symptoms of EPN. She was treated with intravenous antibiotics alone. A follow-up abdominal CT scan revealed the complete disappearance of the features of EPN.