Introduction Thyroidectomy and parathyroidectomy, can damage recurrent laryngeal nerves, we propose a new method for the stimulation of the vagus, not invasive, that allows also to differentiate right and left RLN. Methods In a total of 145 patients undergoing thyroidectomy and parathyroidectom, two subdermal needle electrodes were placed, the cathode on the angle jaw, and the anode on mastoid, bilaterally, reaching the carotid triangle in the upper neck, so we can stimulate vagus nerve without dissection. Using single stimulus, 0.2 ms of duration, intensities from 15 to 40 mA, an EMG response is obtained in the electrode placed in the endotracheal tube, latency 9–11 ms in right side and 10–13 ms in left side, reproducible, and without variations during surgery. Results We observed latency variations, when a sustained increase of EMG activity was recorded in the laryngeal electrode, while the surgeon was nearby RLN, and also bimodal response in those cases in which LRN division was observed during the dissection.In all them the unilateral LRN stimulation was seen. We also observed the presence of a peripheral silent period confirming the correct stimulation. Provided that we obtain the unilateral stimulation of the nerve, with minimal contraction of cervical musculature and practically not stimulation of the spinal nerve, this not disrupt the surgeon who does not need to stop to value integrity of the recurrent nerve. Conclusion This method, minimally invasive, always accessibly, that allows to value RLN of unilateral form, contributing major control in the monitoring of the nerves, without in none of 145 cases (290 RLN), side effects have been observed. A previous report has been made with transcutaneous stimulation of the vagus nerve, but in our experience, more intensity is needed, and spinal nerve is commonly stimulated, disturbing the surgeon, and it use is more limited.