Endometriosis is an important clinical problem among female reproductive system diseases. The goal of the research was the estimation of: 1/frequency of endometriosis’ occurrence, its localization and co-existence with other lesions within the reproductive organ, 2/value of medical history, ultrasonography and colposcopy in endometriosis’ diagnosis, 3/efficiency of the applied therapeutical methods. The data obtained from 574 patients with histoligically confirmed endometriosis, who were operated on in the Chair of Gynaecology and Oncology of the Jagiellonian University in Cracow between 1998 and 2001 were analysed. On the basis of the results it was formulated, that endometriosis is one of the most frequent changes in the area of the female reproductive system and in the highest percentage it concerns adnexa and corpus of uterus. The medical history data as well as ultrasound examination and colposcopy allow to make preliminary diagnosis, which is in nearly 80% cases in accordance with the final one. Endometriosis is accompanied most often by myomas, mild adnexa changes and cervical intraepithelial neoplasia. Quite often endometriosis concerns women, who previously had surgical interventions in the area of the reproductive system, which can confirm implantation theory of the pathogenesis. Colposcopy allows to detect endometriosis’ foci of cervix, whose frequency of occurrence equals about 15% and is higher than it was previously thought. Implementing pharmacotherapy after conservative surgical treatment does not influence the amount of endometriosis' recurrences, but usually decreases pain.