Gelastic (laughing) epilepsy characterized as paroxysmal involuntary laughing episodes usually begins in infancy or childhood. It is known to be poorly respond to medical or surgical treatments. This unique seizure is rare and associated with variable etiologies, especially with hypothalamic harmatoma. But still, relationship between harmatoma and seizure is unclear. We presented three cases of gelastic seizures which were diagnosed by clinical history, 24 hour video EEG monitoring and radiological studies. Two of them were associated with hypothalamic harmatoma, but etiology of one case with normal brain structure can not be documented. Anticonvulsant agents were prescribed on all cases and surgical interventions(gamma knife surgery or subtotal resection) were done on harmatoma cases. After medical and surgical treatments, one case showed poor prognosis but two cases showed exellent outcome with seizure free state.