Patients undergoing acute or elective surgical procedures of the upper extremity and shoulder received an interscalene block of the brachial plexus, using the technique described by Winnie, with the slight modification that we did not search for paresthesias. The local anesthetic solution used was 30ml of 1.5% mepivacaine without adrenaline. The plexus block was successful in 24/35 (69%). A remarkable feature is the reliable analgesia obtained in the proximal part of the upper extremity, the shoulder and even part of the neck. However, analgesia of the forearm and hand, corresponding to the medial antebrachial cutaneous nerve and the ulnar nerve, was lacking in 20 and 29%, respectively. Complications included were concurrent block of the phrenic (one case) and recurrent laryngeal (one case) nerves. Horner's syndrome was present in five patients. This procedure has the advantage over other approaches for the bracnial plexus block in that the risk of arterial puncture is minimized and the possible occurrence of pneumothorax can be avoided.