Although the effects of aspirin on the oral mucosa are well-documented, there is little documentation of the effects of aspirin-chewing on the enamel and dentin.The authors present two cases of patients with damage to their tooth enamel and dentin. Both patients had similiar symptoms, but had not been told that chewing aspirin could harm tooth structure. The authors identify clinical signs and symptoms and discuss ways to prevent erosion.The common factor in these cases is that aspirin was the only possible cause of the tooth erosion. Dentists should be aware of the effects of aspirin-chewing on tooth structure and advise their patients accordingly.