Two cases of primary antiphospholipid syndrome are described. A girl presented with myocardial infarction at the age of 6. afterward developed chorea, livedo reticularis, thrombocytopenia and circulating lupus anticoagulant (LAC). A boy, age 7, had an episode of intracranial hypertension and a deep venous thrombosis of a lower left limb, both recurrent in the following years. A high titer of IgG anticardiolipin antibodies (aCI) was detected. These observations suggest that both LAC and aCI tests should be performed in children with thromboembolic phenomena when the criteria for a definite autoimmune disease are lacking.