The case history of a patient with pulmonary embolism 4 months following a kidney transplantation is presented. Ultrasonography of the abdomen suggested a large ovarian tumour for which she had a laparotomy. Histological examination after resection of the tumour revealed a benign multicystic mesothelioma of the peritoneum. During the course of 1 year the tumour recurred 5 times and different attempts to aspirate and obliterate the cyst were ineffective. Eventually, cure was achieved by permanent transvaginal catheter drainage, which resulted in infection and obliteration of the cyst.