The evidence accumulated in the literature over the last 10 years points out that the primary treatment of otosclerosis with the endoscopic technique, permits to obtain outcomes which are similar to traditional microscopic surgery. Those results support the use of endoscopic stapes surgery as valid alternative to traditional microscopic surgery. However, there are situations where endoscopic stapes surgery can be a true advantage over the traditional microscopic surgery. These situations are revision stapes surgery, challenging anatomical abnormalities or variations of the oval window niche and malformations of the middle ear and oval window niche area. The aim of the instructional course is to show the surgical technique, possibilities and advantages of endoscopic stapes surgery. The management of difficult situations, malformations and revision surgery, as well as surgical tips will be presented.