Ten football players seen from 1973 through 1977 at the University of Wisconsin Hospitals were found to have clinical and electrodiagnostic evidence of injury to the upper trunk of the brachial plexus. Each had upper limb paresis following one or more blows to the head or shoulders. The development of persistent weakness often was preceded by burning paresthesias in the upper limb. Our experience suggests that the syndrome of burning paresthesias and subsequent arm weakness frequently is secondary to stretching of the brachial plexus.