This study from a community hospital documents the relatively frequent occurrence of Actinomyces in 36 women diagnosed by Papanicolaou stained cervicovaginal smears. Actinomyces was identified exclusively in patients wearing an intrauterine or vaginal foreign body (intrauterine devices and pessaries). By using fluorescein isothiocyanate labeled antiserum, the organisms were shown to be Actinomyces israelii in eight randomly selected smears. In five cases Actinomyces was demonstrated in tissues obtained by endocervical and endometrial curettage. Anaerobic microbiologic studies performed in 11 of the 36 cases showed a relatively high rate of recovery of Actinomyces (36.3 per cent) with a yield of four positive cultures. In two cases the isolated organisms were shown to be Actinomyces israelii. In the remaining two cases the exact species of Actinomyces has remained uncertain. Of the 36 patients with smear evidence of Actinomyces, nine (25 per cent) had pelvic inflammatory disease, a rate that appears to be much higher than the already high rate among all intrauterine device users. This observation underscores the importance and clinical significance of the finding of Actinomyces in the vaginal smears of intrauterine device users. Papanicolaou stained cervicovaginal smears provide a relatively easy, inexpensive, fast, and highly specific method for the morphologic diagnosis of Actinomyces and allows us to recognize at a relatively early stage a group of patients who are potentially at risk for the development of pelvic inflammatory disease and its associated more severe complications. The hope is that prompt identification of Actinomyces in cervicovaginal smears can help to prevent the more serious infectious complications in intrauterine device users.