Five cases of intrauterine device (IUD)-associated tuboovarian actinomycosis are presented. The patients' ages ranged from 33 to 49 years and their IUD usage from 2 to 12 years. Clinical features of the cases included stenosis of the sigmoid colon in 4 cases, ureteric or bladder obstruction in two cases, and rectal fistula in a further instance. All patients were successfully treated postoperatively with penicillin or ampicillin. An initial diagnosis of ovarian carcinoma was considered in all cases. Although Actinomyces is difficult to differentiate histopathologically from microorganisms and other substances that cause the Splendore-Hoeppli phenomenon, morphological diagnosis permits a quicker and more practical approach than bacterial cultures in the establishment of postoperative antibiotic treatment. Intraoperative frozen-section diagnosis of an acute inflammatory process permits the surgeon to make an immediate decision in order to avoid extensive surgery when ovarian carcinoma is suspected.