A 40-year-old man presented with chronic mouth ulcer for the last six months. Histopathological examination of the biopsy from the lesion confirmed a diagnosis of histoplasmosis. Although histoplasmosis commonly manifests in immunocompromized patients, like HIV, the present case was negative for HIV. Histoplasmosis is endemic in certain parts of the world and it is comparatively rare in the South Asian region, particularly Malaysia. Thirty-seven cases of histoplasmosis were reported from Malaysia (Ng and Siar, 1996), between July 1967 and October 1997. Despite the apparent rarity of the disease, clinicians and pathologists should be aware of the possibility of histoplasmosis when cases of oral ulcer are encountered.