27 patients of the department of gynecology and obstetrics of the university of Essen received a six month therapy with the GnRH-analogon triptorelin because of endometriosis diagnosed by laparoscopy. All the patients experienced not only a significant improvement in their subjective symptoms but also in their rAFS-score which was used to classify the severity of the endometriosis of our patients. We could also show that no patient experienced any severe side effects under the therapy and those side effects such as hot flushes or sweating, which appeared, were almost tolerated very well by the patients. None of the patients did leave the study because of the side effects. We were also able to demonstrate that under the therapy there was no significant loss of the bone density. The introduction of the GnRH-analogon triptorelin is therefore a major step forward in the effective therapy of patients suffering from endometriosis.