Antiphospholipid antibodies predispose to venous and arterial thrombosis. The case of a sixteen-year-old boy with primary antiphospholipid syndrome is presented. Features of different organ involvement such as thrombosis of the inferior vena cava, pulmonary thromboembolism and cerebral involvement were present with thrombocytopenia and high titre of anticardiolipin in the patient's sera. On twelve-month follow-up while taking anticoagulant the patient was entirely free of symptomes though certain immunological findings showed slight positivity. However, considering the ARA criteria systhemic immunopathologic disorder could not have been proved. Other pathological conditions with anticardiolipin positivity were also excluded.