Emphysematous pyelonephritis is a rare and severe suppurative infection of the renal parenchyma and the pen renal tissue that is characterized by gas formation within or around the kidney. The disease usually occurs in diabetic patients and has a high mortality rate. We report a diabetic patient who suffered from chills, fever and left flank pain for 3 days. A plain abdominal radiograph and an ultrasonograph allowed the diagnosis of emphysematous pyelonephritis. She recovered well after adequate medical treatment combined with nephrectomy. The initial investigation of diabetic patients with pyelonephritis and sepsis should include a plain abdominal radiograph together with ultrasonography.