Introduction: Our purpose was to remove large-volume staghorn calculi with less morbidity and maximum ease without an anatrophic nephrolithotomy, with the use of a pneumatic lithotriptor during pyelolithotomy to disintegrate the branches of stones extending into the calyces and retained calyceal fragments. Patients and Methods: Sixteen patients (17 renal units) with large-volume staghorn stones were evaluated with blood urea nitrogen (BUN), creatinine levels, urinalysis, and culture, excretory urography (IVP), and (99m)technetium dimercaptosuccinic acid (DMSA) renal scintigraphy preoperatively. Patients were treated with a pneumatic lithotriptor at the time of open pyelolithotomy. Bilateral surgery was performed in 1 patient. The mean follow-up period was 12 (range 6-24) months. The patients were re-evaluated postoperatively at 6 months with BUN and serum creatinine measurements, urinalysis and culture, IVP, and renal scintigraphy with DMSA. Data were analyzed by one-way ANOVA test. p < 0.05 was considered statistically significant. Results: After treatment, 15 of 17 renal units (88%) were rendered stone-free while residual fragments remained in two patients. Average operation time was 190 min ( range 135-285) with a mean blood loss of 226 ml ( range 140-425). No patient required blood transfusion. Average length of hospital stay was 4.2 days ( range 3-7). Six months after surgery, mean BUN and creatinine levels were decreased from 31.2 to 28.2 mg/dl (p = 0.248) and from 1.3 to 1.1 mg/dl (p = 0.001), respectively. Renal scintigraphy with DMSA revealed an increase in ipsilateral average renal function from 39 to 43% (p = 0.043). IVP also revealed a decrease in pelvicalyceal dilatation in almost all patients with a well-functioning kidney and without any stone recurrence. No complications were encountered postoperatively except for an episode of high fever in 1 patient. Conclusion: Avoiding incision of the renal parenchyma and arterial clamping, without significant bleeding and the nephron loss seem to be the advantages of this technique. Kidney function can be preserved with this simple and easily applicable method, which may be an alternative procedure to anatrophic nephrolithotomy for the majority of patients with staghorn calculi requiring open surgery. Copyright (C) 2004 S. Karger AG, Basel.