PIP: Although over 300 cases of pelvic actinomycosis have been published, it was not until 1973 that the 1st case of pelvic actinomycosis associated with the new generation of IUDs was described. Data is provided in this article on the causative agent, laboratory procedures, surgical excision, and pathological studies in 1 case of abdominal-pelvic actinomycosis, and the findings are compared to other reports in the English and Spanish literature. A multipara of 25 years with fever, metrorrhagia, and painful tumoration began to suffer dysmenorrhea in June 1980 but attributed the symptoms to the Copper 250 Multiload IUD she had used since July 1979. A laparotomy in December 1980 disclosed the infection, and pathological tests confirmed the diagnosis. The exact incidence of the association of actinomycosis and the IUD is not known, but the microorganism, Actinomyces-Israeli, is more common in wearers of IUDs than in other women. The diagnosis of actinomycosis is confirmed through microbiological study and histological identification. Treatment since 1945 has consisted of large doses of penicillin over long periods of time, but the use of other antibiotics including tetracycline and erythromycin has been introduced. The abscess or abscesses should be excised and the IUD removed in cases where a relationship is suspected.