A case of actinomycosis presenting as tubo-ovarian abscess, misdiagnosed as ovarian malignancy in 54-year old woman with IUD is reported. Author presents the diagnostic problems due to uncommon location, no reliable clinical manifestation and nonspecific CT imaging findings, based on current literature. Knowledge of the characteristic features may help one consider the possibility of actinomycetic infection in the differential diagnosis, in patients with a previous history of predisposing factors and treat them appropriately.