Involvement of the attached gingiva by aphthous stomatitis is considered uncommon. This report presents two cases in which patients with aphthous stomatitis developed ulcers on multiple mucosal surfaces, including the attached gingiva. The gingival ulcers began on the marginal gingiva and enlarged to form V- or U-shaped ulcers on the attached gingiva. Other disorders producing gingival ulceration were excluded on the basis of history, clinical features, bacterial culture, viral culture, and biopsy with routine microscopic study as well as direct immunofluorescence.