The limitation of the present study was the small number of patients in the study group (n = 40), this may explain why there is no association between known risk factors and the occurrence of aspirin resistance in multivariate analysis. Some data such as life style modification, smoking, alcohol drinking, and exercise were missing because the medical records were not complete and dif fi culty in interviewing post stroke patients. Drug compliance is a major factors for laboratory non-response to aspirin. Aspirin compliance in the present study was based upon a response to questionnaire and not confirmed by pill count or salicylate levels. Thus, the authors could not exclude the poor compliance as the causes in some cases with aspirin resistance or semi-responsiveness.