Medical oestrogen suppressive therapy has to be considered as an important principle in the management of endometriosis. In the last years GnRHa became the "gold standard" as pre or postoperative measures before/after surgical intervention. We analyzed the data of 198 patients, most of them with recurrent endometriosis histologically confirmed during first-look laparoscopy. Patients were treated in a prospective, multicentre phase III study with the six months GnRHa leuprorelinacetate depot (LAD) followed by a second-look laparoscopy for precise assessment of therapeutic effects. In all stages of endometriosis a 35% reduction of the r-AFS-score compared to the baseline could be achieved due to surgical intervention during first-look laparoscopy with a further improvement of 64% after GnRHa-therapy and surgery during second-look laparoscopy. Two subgroups of patients (24 vs. 45) could be analyzed according to the time of second-look laparoscopy (< or = 30 days vs. > or = 60 days after last injection) showing a comparable r-AFS-score reduction. Both, superficial lesions and deep infiltrating nodules, endometriomas, peritoneal implants and obliterated cul de sac could successfully be treated through the combined medical-surgical approach. Pre- or postoperative therapy with a GnRHa facilitates surgical excision of the implants, a subtle adhesiolysis and often complete removal of all visible lesions. In a high percentage of patients, including advanced stages of the disease, a preservation of ovarian tissue to ensure the childbearing potential could be achieved by minimal-invasive techniques. These results can be claimed as the prerequisites for long-term relief of endometriosis complaints and encouraging pregnancy rates in endometriosis related infertility. This confirms great clinical benefit of the combined medical-surgical approach for the treatment of this enigmatic disease.