Pyelonephritis is a frequent infection of variable severity. Mortality is low since the era of antibiotics. Emphysematous pyelonephritis is however a rare but life threatening form of kidney infection, which affect more frequently diabetic subjects, characterized by gas producing bacteria. These gaseous lesions can be localized in the renal parenchyma or in the perirenal or retroperitoneal space. Diagnosis became easier with the advent of CT scan. Treatment usually requires surgery and antibiotics. We report a case of emphysematous pyelonephritis in a diabetic patient. The CT scan strongly suggested the diagnosis which was confirmed per-operatively. Proteus mirabilis is exceptionally described in emphysematous pyelonephritis.