High radial nerve palsy occurred in a 47-year-old athlete following muscular overexertion. Surgical exploration showed a fibrous arch coming from the long head of the triceps and causing entrapment of the radial nerve. Radial nerve entrapment following muscular overexertion has been reported to be caused by fibrous arches coming from the lateral head of the triceps. Fibrous arches can occur from either the lateral or long head of the triceps muscle. The neuropathy that occurs can be irreversible.