Seventeen patients were subjected to analysis of various renal functional parameters before and after extracorporeal shock wave lithotripsy (ESWL) for renal stones. Thirteen patients were observed at 2 weeks and 3 months. Glomerular filtration rate (GFR) was not influenced by ESWL as based on unchanged serum levels of creatinine, beta 2-microglobulin and creatinine clearance. A significant increase in urinary excretion of beta 2-microglobulin, N-acetyl-beta-glucosaminidase and alkaline phosphatase, with return to pre-treatment values within 4 to 5 days, reflected transient disturbances in proximal tubular function. Urinary albumin excretion was increased 0-24 h after ESWL. No significant alterations were observed in plasma renin activity or serum aldosterone due to ESWL. Serum lactic dehydrogenase remained significantly increased for 2 weeks. In addition, significant changes in several blood and urine parameters were caused by immersion in water and intravenous infusions during treatment and were not specifically due to ESWL.