By means of transcranial magnetic stimulation bilateral compound muscle action potentials of long latency and ipsilateral potentials of short latency can be obtained in muscles supplied by cranial nerves. In this study motor evoked potentials were recorded from the mentalis muscle of 14 patients with traumatic brain lesions. These results were compared with clinical and radiological as well as other neurophysiological examinations. In spite of the absence of paralysis in muscles supplied by the facial nerve, 9 patients showed pathological long-latency responses, which correlated with the localisation of the paralysis of the limbs. In contrast to this, the degree of pathological latencies of motor evoked potentials did not correspond with the degree of paresis in different patients. A prediction concerning the clinical outcome could not be made by the results of motor evoked potentials. The clinical data showed a poor correlation with the structural brain lesions seen in the CT-scan and the results of EEG, BAEP and orbicularis oculi reflex examination. In conclusion, transcranial magnetic stimulation of cranial nerves proved to be a sensitive method for the evaluation of degree and localization of motor deficits following traumatic brain lesion and seems to be superior to the other examinations compared.