This retrospective study compares the results of two surgical procedures, a transaxillary and a transthoracic (that is, anterolateral thoracotomy) approach, in the treatment of the thoracic outlet syndrome by first rib resection. After transaxillary first rib removal (13 cases), initially our procedure of choice, 84% of conditions were improved, 8% were unchanged, and 8% were worse after 1 year. One permanent, disabling brachial plexus injury occurred after this operation. Transthoracic first rib resection (18 cases), presently our preferred technique, resulted in improvement in 87% of cases, with 13% of symptoms unchanged after 1 year. Although two female patients felt mild paresthesia of the mammary gland, no one has been made worse following this route. These two approaches have achieved similar results in the surgical management of this syndrome. Nevertheless, when first rib resection is indicated, our favored and recommended procedure is transthoracic, because this route appears less hazardous for brachial plexus damage.