Actinomycosis is a chronic suppurative granulomatous disease caused by the Gram-positive bacteria Actinomycoses israelii. This infection rarely involves the pelvis where the main etiological risk factor is the use of an intra-uterine contraceptive device. We report on a case of pelvic actinomycosis which mimicked ovarian neoplasia both clinically, radiologically, and surgically. The final diagnosis was made based on the histopathology study of the removed organ. The clinical picture is often nonspecific and may suggest ovarian neoplasia. First line treatment is essentially medical, involving prolonged treatment with antibiotics. Additional surgical treatment may occasionally be appropriate.