The authors report on a case of juvenile pilocytic astrocytoma (JPA) and concomitant hypothalamic hamartoma (HH) with gelastic epilepsy that was successfully treated with endoscopic disconnection. This 6-year-old girl presented with prolonged, medically intractable gelastic seizures that were often followed by generalized tonic seizures. An enhancing, low-grade hypothalamic tumor was identified on MR images obtained when she was 11 months old, but no surgical intervention was attempted at that time apart from bur hole drainage of a chronic subdural hemorrhage. In the first surgery, performed when she was 6 years of age, the authors attempted disconnection and tumor sampling; the lesion was revealed to be a JPA. A second endoscopic disconnection was performed 1 year later to improve seizure control and obtain a pathological specimen from the nonenhancing contralateral side. The pathological results after the second surgery revealed that the enhancing mass was a spontaneously regressing JPA and the contralateral nonenhancing mass was an HH. The HH was found as latent tumor and the JPA was the mass causing gelastic epilepsy. To the authors' knowledge, this is the first report of a patient with a spontaneously regressing JPA and concomitant HH, both of which were treated by endoscopic disconnection