Summary— We have treated 167 patients with staghorn calculi. Conservative therapy was used in 61 patients who have been followed up for 1 to 18 years (average 7.8). Chronic renal failure occurred in 22 of these patients and 7 died from uraemia. The causes of chronic renal failure were bilateral staghorn calculi, staghorn calculi and contralateral urinary calculi, and chronic pyelonephritis of the contralateral kidney. The morbidity and mortality rates following conservative treatment were higher than those following surgical management. The pathological findings in 47 kidneys after nephrectomy showed severe hydronephrosis, renal abscess and xanthogranulomatous pyelonephritis. These results indicated that staghorn calculi destroyed the kidney and early complete removal of these stones is advisable.