A family is described in which venous thromboembolic disease is associated with reduced plasma protein C activity and normal levels of protein C antigen. Immunoelectrophoretic analysis of protein C antigen gave an abnormal pattern in all affected members, suggesting that the disorder is related to the presence of a structurally and functionally abnormal form of protein C. The propositus developed simultaneous warfarin-induced skin necrosis and bilateral adrenal hemorrhage. This is the first reported instance of warfarin-induced skin necrosis associated with a dysfunctional protein C molecule and the first reported instance of simultaneous warfarin-induced skin necrosis and bilateral adrenal hemorrhage.