Endometriosis, including endometriosis externa, endometrioma, adenomyois, adenomyomas, adenomyotic nodules of the uterosacral ligaments, and endometriotic nodules, such as scar endometriosis are effectively treated by the intralesional administration, including transvaginal, endoscopic or open surgical administration including via laparotomy, of a progestogen. Compositions therefor also are provided.