We investigate the clinical outcome from stimulation of the mamillothalamic tract in two patients with intractable epilepsy secondary to hypothalamic hamartomas. One patient has a left-sided and the other a right-sided tumor. Both patients presented with a history of gelastic and complex partial seizures resistant to multiple antiepileptic drugs. Both patients underwent insertion of a single deep brain-stimulating electrode ipsilateral to the site of the tumor, lying adjacent to the mamillothalamic tract. Postoperatively they both had a significant reduction in seizure frequency, with one patient being seizure free for the last 10 months. An improvement in mood was reported by the patient's primary carers and demonstrated on quality of life questionnaires.