Non-operative management has frequently been adopted for closed injuries of the infraclavicular brachial plexus and its branches in the belief that spontaneous recovery is likely to occur, and surgical exploration is performed only if recovery has not occurred in the expected time. This paper correlates the clinical and electrophysiological features with the operative findings in six patients with such injuries. The axillary nerve was ruptured in all six patients, the musculocutaneous nerve in two and the radial nerve in two. When the muscles supplied by a branch of the plexus were denervated, the differentiation between rupture of that branch and a lesion in continuity could only be made by surgical exploration, which should be performed as soon as other injuries permit.