Objective: to describe and evaluate the postoperative analgesic effectiveness of the combination of morphine, dexamethasone and local anesthetic in ultrasound-guided brachial plexus block.materials and methods: A prospective, observational and analytical cohort study was conducted.The cohort was composed of 106 patients divided into three groups: 1. Local anesthetic (AL), 2. Local anesthetic plus dexamethasone (ALD) and 3. Local anesthetic plus dexamethasone and morphine (ALDM).the outcome variable was acute postope-