Interscalene brachial plexus block is one of the most popular upper extremity blocks in use all over the world, since first described in 1970 by Alon P. Winnie. It is a simple, safe and effective anesthesia for all types of surgery on the shoulder and upper arm. Easy palpable landmarks, the lack of significant patient positioning requirements, the need for minimal patient cooperation and the high success rate make the interscalene approach a very popular regional anesthesia technique for ambulatory arthroscopic shoulder surgery. Hemidiafragmatic paralysis occurred in almost 100% of the cases and ventilatory insufficiency is one of the contraindications for this block. Special attention to the patient in the sitting position must be taken to avoid activation of the Bezold Jarish reflex. Correct identification of the interscalene groove, using short needles with a mesiad, dorsal and slightly caudal direction, correct interpretation of paresthesia or obtaining a motor response with a metameric characteristic that includes the flexion of the arm due to C6 stimulations, are the most important keys of success and lessening of complications for this technique.