Adult giant hydronephrosis is a rare clinical entity. His clinical diagnosis is not obvious. We report a case of a 42-year-old man, who was admitted for a large intra-abdominal mass, painless, evolving for about 8 months. The clinical examination showed a very distended abdomen. The abdominal CT confirms the diagnosis of left giant hydronephrosis on ureteral lithiasis. Surgical treatment consisted of an emergency percutaneous nephrostomy followed by a secondary left nephrectomy. The evolution was favourable and the aftermath were simple.