Systemic capillary leak syndrome (SCLS), also called Clarkson's disease is rare and life-threatening disorder of unknown etiology, which is a characteristic triad of hypovolemic shock, hemoconcentration, and hypoalbuminemia. Unexplained capillary leakage from the intravascular to the interstitial space, which has been estimated up to 70% of the intravascular volume, is the proposed mechanism. Because the pathogenesis is unknown, it is diagnosed clinically after exclusion of other diseases that cause systemic capillary leak and no efficacious pharmacological treatment has been clearly established. The mortality rate ranges from 30% to 76%. In Korea, four cases of SCLS (5 cases in adult and 1 case in child) were reported by 2012. We describe a case of severe SCLS that suddenly occurred and rapidly progressed during pylorus preserving pancreaticoduodenectomy and review the literature.