Emphysematous pyelonephritis is an acute gas forming necrotizing infection of the renal parenchyma with high mortality, which shows non-specific clinical findings. Elderly patients with altered mentality and shock require careful monitoring and abdominal computed tomography scanning is thought to be beneficial in prompt detection of infection focus and management. We report on a patient with altered mentality who showed emphysematous pyelonephritis on abdominal computed tomography and provide a review of the literature.