Function of the peroneal nerve should be evaluated in all patients with a history of inversion ankle sprain. Two cases were presented that demonstrated significant involvement of the common peroneal nerve following ankle injury. Manual muscle testing and sensory exams identified the involvement of the peroneal nerve, and electrophysiological testing localized the lesion and provided indications of the severity of the trauma. The importance of routinely performing neurological testing on patients with ankle sprains as part of initial and follow-up evaluations has been demonstrated and is supported in the literature.