We describe the first case of catastrophic antiphospholipid antibody syndrome (APS) in a patient with progressive systemic sclerosis (SSc). After initial presentation with digital gangrene the patient developed rapidly progressive multiorgan failure and died within 19 hours. Postmortem examination revealed extensive multiorgan arterial microthrombi of days' to months' duration. This suggests that a subclinical state of thrombosis existed before onset of catastrophic APS. Given the poor prognosis of established catastrophic APS there is a need for a means to detect subclinical thrombosis and treat "at risk" patients before clinically apparent thrombosis occurs.