Two patients with obstructive uropathy as a result of post menopausal endometriosis are reported. They both illustrate the potential problems of hormone replacement therapy after bilateral salpingo-oophorectomy and hysterectomy in patients who have had extensive endometriosis. It is suggested that in such patients the potential of reactivation of the disease with hormone-replacement therapy should be recognised and ureteric involvement be excluded by intravenous urography or renograms.