We report the case of a two years old boy showing gelastic fits as the leading clinical symptom of a rare complex cerebral malformation with closed-lip schizencephaly, an arachnoid cyst and a partial agenesis of the corpus callosum. After 5 uneventful interictal electroencephalograms the patient underwent 24 h EEG with telemetry while finally presenting two laughing fits with associated spike-wave discharges in the right-centroparietal region. Medical treatment with carbamacepine was initiated and the seizure frequency decreased significantly. This is the first cited case of gelastic fits occurring in schizencephaly. In contrast to previously cited cases with laughing fits we observed a good response to anticonvulsive treatment. Moreover our patient presented a surprisingly favourable psycho-mental and motor development during an 8 months observation period.