A series of 10 instances of genital actinomycosis infection complicating the use of intrauterine contraceptive devices is recorded and its pathogenesis described. The likelihood is suggested that this complication is more frequent than is generally appreciated. A pathway of infection extending upward from the patient's anus, across the perineum, and up the vagina and cervix is suggested as the route of infection. The traumatizing effect of the device and a previously existing or intercurrent infection as additional contributing factors to the development of actinomycotic infection in the female genitalia is also postulated.