Leiomyomatosis peritonealis disseminata is a rare disease. Approximately 50 cases have been reported in the world literature so far. Origination from the Müllerian epithelium, which is distributed throughout the subperitoneal mesenchyme seems possible in histogenesis. By specific hormonal stimulation and individual predisposition proliferation takes place along the lines of myofibroblastic differentiation. The case of a 41 year-old woman is presented. The patient's history revealed hormonal therapy for dysmenorrhoea. An incidental finding during diagnostic laparotomy for suspicious endometriotic ovarian cysts, multiple grey-white, granular nodules were seen covering the peritoneal surface of the small pelvis, the intestines and omentum and the surface of the uterus and adnexal structures, as found with peritoneal carcinomatosis arising from the ovary. Microscopically, the nodules were composed of smooth muscle cells which did not show any a typical appearance or mitosis. Immunohistological investigation with Desmin antibodies confirmed the diagnosis. The benign tumours of leiomyomatosis peritonealis disseminata must be differentiated from peritoneal metastases of malignant tumours in order to avoid unnecessary aggressive treatment schedules. Nonetheless follow-up is desirable since malignant degeneration has occasionally been reported.