Vagus nerve stimulation (VNS) is an increasingly used therapy for patients with treatment-refractory epilepsy and depression. Hypomanic and manic symptoms are a rare but recognized adverse effect of VNS treatment. Here we describe a case in which VNS treatment in a patient with epilepsy and unipolar depression was associated with the rapid development of manic symptoms. The patient's manic symptoms resolved with temporary discontinuation of the VNS current, and the patient was eventually able to resume VNS treatment with good effect and without further manic symptoms. Mania is a rare but serious side effect of VNS; however, in this case and in the majority of reported cases of VNS-associated mania, symptoms resolve and VNS can be safely administered.