Primary antiphospholipid syndrome (APS) is a disease producing vascular thrombus with antiphospholipid antibody without association with autoimmune diseases as systemic lupus erythematosus. Retinal vein occlusion is a rare vascular manifestation in primary APS. We describe 2 cases of primary APS presenting with developing blurred vision. Each had central retinal vein occlusion and high titer of IgG anticardiolipin antibody.