Before starting shoulder arthroscopy, we need to know shoulder anatomy, especially the precise location of the nerve to avoid its damage. To understand the three-dimensional anatomical structure, bony land marks including the acromion, clavicle, acromioclavicular joint, and coracoid process are important. Accurate portal placement is crucial when performing arthroscopic surgery. There are a lot of portals for shoulder arthroscopic surgeries. We recommend to use several portals to maximize access to the glenohumeral and subacromial space but do not hesitate to make accessory portals to obtain the best arthroscopic visualization. In this chapter, the relevant anatomy and standard location of portals for shoulder arthroscopic surgery and the use of portal for common procedures are described.