OBJECTIVE This study was designed to determine the incidence of complications in a sample of 6,185 brachial artery punctures for arterial blood gas analysis. METHODS The study sample was comprised of adult patients who had arterial blood gas analysis ordered in the course of their clinical evaluations in a multispecialty clinic and hospital affiliated with a university school of medicine. Subjects were entered prospectively at the time the procedure was done. RESULTS The overall incidence of all complications was 2.0%. Immediate limb pain or parenthesias occurred in 1.1%, while the onset of symptoms was delayed up to 24 h in 0.9%. Hematoma formation occurred in only 0.06%. None of the complications was considered to be of major impact, in that none was associated with limb ischemia or other objective abnormalities. Only one subject required analgesic medication to control pain that ultimately subsided spontaneously without deficit. CONCLUSIONS We believe that brachial artery puncture, when properly performed, is a safe and reliable alternative route for obtaining arterial blood for gas analysis.