The proper treatment of younger patients who have suffered ischemic stroke and who have no stroke risk factors other than antiphospholipid antibodies is unsettled. We propose a rationale to support adding dietary supplementation with calcium and vitamin D to the present standard regimen of anticoagulant therapy for these patients. We expect that the benefits from this additional therapy will prove additive. Proving this hypothesis will require large numbers of patients unlikely to present to any one center. The military health care system is well suited to such a study.