Long term follow up control in 40 cases of Bell’s Palsy which had been treated by decompressive surgery of the facial nerve in its intratemporal course have led us to the following conclusions: Electromyography (EMG) is actually the only method allowing an objective and reliable control of the nervous disfunction during and after its full development as well as during the course of recovery. For this reason every case of Bell’s Palsy ought to be controlled in regular intervals (1–2 weeks) electromyographically from the very beginning of the paresis. Evaluation of operative results following decompression of the facial nerve should be based on the results of repeated EMG-studies and no longer upon the subjective impression of the surgeon following up the patient. EMG examinations performed immediately after the onset of an idio-pathic facial paralysis reveal only one reliable symptom indicating the necessity of a decompression at an early stage: the occurrence of fibrillation potentials. The present study does not give any evidence in favour of the hypothesis that postoperative functional results may be improved by an emergency operation, i.e. by performing the decompression as soon as possible after the onset of the paresis. The majority of total or subtotal facial paralysis recover spontaneously by the end of the 4th week. As long as fibrillation potentials are absent, there is no indication for a decompression during the first 4 weeks. In cases showing no symptoms of spontaneous recovery at the end of the 4th week (e.g. polyphasic muscle action potentials) decompression of the nerve is absolutely indicated, because the chances of a spontaneous recovery during the following weeks or months are extremely small. For this reason no precious time should be wasted. If during the first 10 days, EMG examinations reveal the presence of fibrillation potentials, immediate decompression is indicated.