Acute effects of extracorporeal shock wave lithotripsy (ESWL) with Siemens Lithostar on kidney and surrounding tissues were examined on 42 patients with unilateral kidney stones in the Department of Urology, Gazi University, Medical Faculty, Ankara, Turkey. Radiological examinations were done and 24-h urine and blood samples were obtained a day before, the day after and 30 days after ESWL. Urinary excretion of proteins, glycosaminoglycan, and immunoglobulin G were significantly elevated the day after ESWL. Thirty days after excretion levels of these were statistically insignificant in regard to pretreatment levels. Creatinine clearance of the patients was significantly lowered the day after ESWL. One month later differences were insignificant. Excretory urography detected 12 (29%) kidneys with abnormalities the day after ESWL. Thirty days after only 3 (7%) of the kidneys had persistent abnormalities. The number of abnormalities with ultrasonography 24 h and 30 days after ESWL were 15 (36%) and 5 (12%) respectively. With CT-scanning kidney abnormalities 24 h after and 30 days after ESWL were 24 (57%) and 6 (14%) respectively. There was not any statistically significant difference between patients with either radiological or functional changes after ESWL and with patients without these changes in regard to patient age, sex, stone burden and shock wave number. In conclusion, electromagnetic lithotripsy induces acute renal morphologic and functional changes. Functional changes are transient and subside within a month but although decreasing either in size or number some morphologic changes persist during this period.