Actinomycosis is a rare infectious inflammatory disease caused by the bacteria of the Actinomyces species. Infection occurs following damage to the skin or mucous membrane. This report presents a case of a 50-year-old female patient with subfebrile temperature, weight loss and pain, who used to have an intrauterine device. Masses suggestive of an advanced cancer were detected in her pelvis and abdominal cavity. A diagnosis of actinomycosis was made after histopathological examination of the tissue sample.