This article represents a retrospective study of 12 patients with renal carbuncle treated at the combined urological services of The Mason Clinic in Seattle, Washington, and Madigan Army Medical Center in Tacoma, Washington. All patients were initially treated with antibiotics. Two recovered without further treatment. Of the 10 patients who failed to respond, 2 underwent nephrectomy for nonfunctioning kidneys, 4 underwent closed percutaneous drainage, and 4 underwent surgical open drainage. All patients treated with open surgical drainage recovered and retained functioning kidneys. Of the 4 patients who underwent closed percutaneous drainage, 2 failed to respond and required subsequent emergency nephrectomy because of sepsis. The authors believe that renal exploration and open drainage should be the initial definitive mode of surgical treatment of renal carbuncle in those patients who fail antibiotic therapy alone.