Acute renal insufficiency due to ureteral obstruction is relatively uncommon and gives rise to difficulties of diagnosis and treatment. The series presented here analyzes these aspects in 24 patients who had 27 episodes of proven anuria due to ureteral obstruction. Their average age was 62. Six patients had only one kidney (25%). The most common etiology was cancer (two thirds of the cases), mainly of genitourinary origin (10/16). Calcium or uric acid urethral lithiasis was the main cause of obstruction in the benign group. Treatment corresponded to a wide range of obstruction removal procedures depending on the etiology, but in the secondary to cancer it was very aggressive and the most used was nephrostomy. The decision to perform any treatment of obstructive anuria in patients with cancer should take into account a variety of important aspects amongst which prevail the prognosis of the basal illness, the handling of cancerous pain, the complications and mortality associated with the procedure and the patient's prospects.