Abscess as a complication of extracorporeal shock wave lithotripsy is a rare condition. We present the computed tomography findings of an abdominal wall abscess that occurred after extracorporeal shock wave lithotripsy for which prophylactic antibiotics had not been given. The abscess destroyed the posterior abdominal wall muscles and dissected into the thorax. The muscles were thickened and showed enhancement. A parenchymal defect in the right kidney adjacent to a caliceal stone, with strands extending from this defective region to the abscess, was observed, and was thought to be the result of parenchymal destruction caused by the shock waves. Other parts of the kidney and psoas muscle were normal. Microbiologic examination revealed Escherichia coli.