A case of periapical actinomycosis is presented. Although apparently uncommon, actinomycosis should be considered when a chronic periapical lesion, often in the maxilla, is associated with an endodontically treated tooth or a previous history of trauma. Histologic examination of the tissue or the presence of "sulfur granules" in the exudate will usually establish the diagnosis. Treatment consists of local curettage and antibiotic therapy.