We report the clinical observation of a 23-year-old woman affected by the so-called 'catastrophic antiphospholipid syndrome'. Within a 3-month period she suffered a number of thrombotic events and haemolytic anaemia with thrombocytopenia and had high levels of immunoglobulins G and M and anticardiolipin antibodies associated with lupus anticoagulant activity. The severity of the clinical and laboratory changes is described and diagnostic and therapeutic difficulties are discussed. The apparent control of thrombotic events only with high levels of warfarin anticoagulation is stressed.