Two women had large, solid, fixed pelvic masses simulating advanced ovarian cancer in one case and advanced cervical cancer in the other. Both patients had had plastic intrauterine contraceptive devices in situ for 7 and 17 years, respectively. Both patients required laparotomy to make the diagnosis. In both the surgery was markedly difficult because of the total absence of tissue planes. Both had obvious actinomycotic disease on routine histologic examination of the ovary and were treated with prolonged penicillin, with some, but not total, resolution of the pelvic fibrosis. The diagnosis of advanced actinomycotic pelvic inflammatory disease should be entertained in patients with a large, solid pelvic mass and an intrauterine device in situ or a recent history of intrauterine device use.