SummaryA 36-year-old woman was admitted to the hospital for surgical treatment of a fourth recurrence of right-sided spontaneous pneumothorax. During thoracotomy histologically proved endometriosis of the pleura overlying the right hemidiaphragm was found. About forty days before she had undergone a total hysterectomy and bilateral oophorectomy for pelvic endometriosis, followed by oestrogen implantation.In the discussion a review of the signs and symptoms of thoracic endometriosis is given, along with possible mechanisms of pathogenesis and different ways of treatment.