Anticardiolipin antibodies (aCL) have been recognised as a marker for an increased risk of thrombosis. The prevalence of these antibodies in young Indian ischemic stroke population is not known. Our study establishes the prevalence of these antibodies and evaluates their clinical significance in 60 patients aged 40 years or less who presented with completed ischemic stroke. Immunoglobulin G and immunoglobulin M class antibodies to anticardiolipin were determined using a standardized enzyme-linked immunosorbent assay. The prevalence of these antibodies in stroke patients was 23% compared to 3.2% in the controls. All patients studied had no overt evidence of systemic lupus erythematosus or related autoimmune disorders. The aCL-positive stroke patients did not differ significantly from aCL-negative stroke patients with regard to demographic characteristics, risk factor profile, and radiological features. Prior transient ischemic attacks, ischemic retinopathy, and asymptomatic infection were more frequent in the aCL-positive group. The role of anticardiolipin antibodies as a disease marker for ischemic stroke is under-recognised in India and warrants further investigation.