OBJECTIVE: To report our initial experience with a novel device, designed to provide portable, noninvasive, transcutaneous stimulation of the vagus nerve, both acutely and preventively, as a treatment for cluster headache. METHODS: Patients with cluster headache (11 chronic, 8 episodic), from 2 centers, including 7 who were refractory to drug treatment, had sufficient data available for analysis in this open-label observational cohort study. The device, known as the gammaCore, was used acutely to treat individual attacks as well as to provide prevention. Patient-estimated efficacy data were collected by systematic inquiry during follow-up appointments up to a period of 52 weeks of continuous use. RESULTS: Fifteen patients reported an overall improvement in their condition, with 4 reporting no change, providing a mean overall estimated improvement of 48%. Of all attacks treated, 47% were aborted within an average of 11 ± 1 minutes of commencing stimulation. Ten patients reduced their acute use of high-flow oxygen by 55% with 9 reducing triptan use by 48%. Prophylactic use of the device resulted in a substantial reduction in estimated mean attack frequency from 4.5/24 hours to 2.6/24 hours (p < 0.0005) posttreatment. CONCLUSION: These data suggest that noninvasive vagus nerve stimulation may be practical and effective as an acute and preventive treatment in chronic cluster headache. Further evaluation of this treatment using randomized sham-controlled trials is thus warranted. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for patients with cluster headache, transcutaneous stimulation of the vagus nerve aborts acute attacks and reduces the frequency of attacks.