Catastrophic antiphospholipid syndrome, defined and documented in 1992, is a potentially fatal complication seen in patients with antiphospholipid antibody. It may arise de novo in patients not previously suspected as having an antiphospholipid syndrome, or it may complicate the course of patients currently treated for this syndrome. Precipitating or "trigger" factors have been identified in 55% of patients; the most common of these factors is infection. The precipitating factors should be avoided or energetically treated in patients with the antiphospholipid syndrome in order to prevent this "catastrophic" course. The clinical manifestations are those of multiorgan failure, and unusual vessels or organs can be involved. Treatment of the condition, with emphasis on effective anticoagulation, intravenous steroids, intravenous immunoglobulin, or plasma exchange, should be aggressive to achieve a satisfactory outcome. Regrettably, despite all available therapeutic options at this time, the mortality is still high (greater than 50%).