Renal manifestations of the "primary" antiphospholipid syndrome are rare. We report the case of an athletic 35-year-old man with an unremarkable medical history who suddenly developed hypertension and a renal infarction. Laboratory and radiological investigations showed a complete thrombosis of the infrarenal aorta, extensive collateral circulation arising from the superior mesenteric artery, and the primary antiphospholipid syndrome. Eight cases of renal infarction have previously been reported in the primary antiphospholipid syndrome. To our knowledge, this represents the first case of an infrarenal aortic thrombosis attributable to this syndrome.