Systemic Capillary Leak Syndrome (SCLS) is a rare and recently discovered disease. The diagnosis must be evoked in front of an hypovolaemic shock associated with a refractory anasarca. We report an observation of SCLS and then discuss the diagnostic and therapeutic difficulties. SCLS is diagnosed when a patient meet a compatible clinical situation with an hypoalbuminemia in spite of relative hemoconcentration. Evidence of a monoclonal gammapathy constitute an additional clue.