Systemic capillary leak syndrome is a rare condition characterized by unexplained episodic capillary hyperpermeability. A shift of fluid and protein from the intravascular to the interstitial space results in hypovolaemia. Attacks vary in frequency, severity and duration and can be fatal, although they often remit spontaneously. During acute episodes there is a pathognomonic elevated haematocrit and reduced serum albumin, frequently associated with a monoclonal gammopathy. Treatment has been largely empirical but there are anecdotal reports of beneficial therapy. We describe a further case which highlights the typical clinical presentation, course and investigate findings and review the other cases described.