We assessed whether initial clinical presentations suggestive of antiphospholipid syndrome (APS) predicted the subsequent rate and type of serious clinical outcomes. Eighty-two consecutive patients with anticardiolipin antibodies or lupus anticoagulant were followed for 814 person-years after a first event suggestive of APS (livedo reticularis, thrombocytopenia, autoimmune haemolysis, thrombosis, central nervous system manifestations, recurrent abortions). The hazard of developing a second event was largest in patients with antibodies recognizing beta2 glycoprotein I who had autoimmune haemolysis as the first event (hazard ratio HR 2.70, p=0.018) and smallest in patients without such antibodies who had recurrent abortions as their first event (HR 0.37, p=0.028). Subsequent serious events in patients with venous and arterial thromboses, recurrent abortions, central nervous system manifestations and autoimmune haemolytic anaemia were likely to be of the same type as the presenting event (odds ratio (OR) 3.76, 5.90, 77.7, 6.92, and 7.13, respectively. Adjusting for therapy, the rate of subsequent serious events was 6.86-fold higher (p=0.0001) in patients presenting with two events, 1.56-fold higher (p=0.038) in autoimmune haemolysis presentations, 1.69-fold higher (p=0.004) in patients with anti-beta2-glycoprotein-I antibodies, and 46% (p=0.063) lower in thrombocytopenia presentations. Initial clinical features determine the long-term evolution of APS, and specific types of clinical manifestations cluster during the course of the disease.