The systemic capillary leak syndrome is a rare condition, with a high mortality rate, characterised by recurrent episodes of generalized edema, with hemoconcentration and hypoproteinemia, associated with paraproteinemia. Pathophysiologically, this syndrome is caused by a sudden, reversible increase in capillary permeability, with a rapid shift of plasma from the intravascular to the extravascular compartment with subsequent hypovolemic shock. We report a new patient of this unusual condition, and we review its diagnostic and therapeutic aspects.