THE LAST decade has seen an ever-increasing interest among urologists in the subject of pyeloplasty. More widespread knowledge and experience with the many procedures in vogue, together with the aid of antibiotic and chemotherapeutic agents, have unquestionably improved the outlook in hydronephrosis. Pyeloplasty is being utilized with greater confidence and success, and because of this fact, fewer hydronephrotic kidneys are being subjected to nephrectomy. However, there is still need for further evaluation of end-results and of the many ingenious techniques of pyeloplasty. There is still wide divergence of opinion as to the choice of treatment in ureteropelvic obstructions. The final answer has not been given as to which is the best type of pyeloplasty for a given type of obstruction. During the past five years, 54 patients with hydronephrosis due to ureteropelvic obstructions have been operated on at Letterman Army Hospital. In 30, or 56%, of these patients, the condition