The occurrence of the nephrotic syndrome during mycosis fungoide is very unusual. We report a rare case of mycosis fungoide revealed by hydrops related to nephrotic syndrom in a 37-year old male patient. He has been admitted to intensive care unit because of a breathing distress and a hydrophobs. Whole body computed tomography scan revealed bilateral axillary, cervical lymph nodes, tumoral infiltration of the subcutaneous tissue in the cervicothoracic and abdominal regions, multiples bilateral pulmonary metastasis, bilateral pleural effusion, and abdominal effusion; the kidneys were normal. The patient was staged IVb (T3N3M1). He was treated with CHOP (cyclophosphamide, Doxorubicin, Vincristin and prednisone). Evolution after eight cycles of chemotherapy was spectacular. The development of nephrotic syndrom secondary to mycosis fungoide is rare. It requires a multidisciplinary approach with nephrologists and oncologists.