The authors report on a series of 50 consecutive patients, admitted in emergency for complete urine retention of sudden onset. They all presented an enlarged bladder, containing 500 to 2 200 ml of urine. They all underwent vesical drainage through urethral catheterization, without concern for a slow decompression of the bladder. There were six cases of macroscopic hematuria needing no specific treatment. For the authors, there is no justification for slow urinary decompression.