Some renal calculi are borderline indications for either extracorporeal shock wave lithotripsy (ESWL) or percutaneous nephrolithotomy (PCNL). Our purpose was to quantify by single photon emission computed tomography (SPECT) the parenchymal lesions of these two procedures to make the choice easier. The SPECT study was done before and 30 days after the stone treatment. The scan was carried out 10 hours after injection of 99mTc-DMSA using a GE400 rotative gamma camera, which data were reconstructed in three planes. The local uptake and scar of the treated area were evaluated in 22 patients with symptomatic kidney stones without previous treatment or renal failure. Twelve patients (mean stone size 12 x 9 mm) were treated on a piezoelectric (EDAP LT-01) lithotripter (mean shock wave number 3420), and ten patients (mean stone size 24 x 17 mm) were treated by PCNL (32F Amplatz sheath in a lower calix). There were no complications, and the stone-free rate at day 30 was 50% in both groups. In the ESWL group, all of the kidneys demonstrated a loss of local uptake, whereas 7 of the 10 in the PCNL group did so. In the ESWL group, 4 of the 12 kidneys had a local loss exceeding 4% but only 2 of 10 kidneys in the PCNL group. There were 7 scars in the treated area in the ESWL group and 6 in the PCNL group. Extracorporeal lithotripsy does not seem to be a nontraumatic procedure for the kidney. For stones that would require several sessions of ESWL, the use of PCNL must be preferred.