Inverted duplicated chromosome 15 (idic (15)) is the most common of the heterogeneous group of the supernumerary marker chromosomes (SMCs). The idic (15) distinct behavior disorder has been described as autistic or autistic-like. Epilepsy represents one of the main clinical challenges in idic (15) individuals. It occurs with a wide variety of seizures, with onset between ages 6 months and 9 years. Infantile spasms associated with an hypsarrhythmic electroencephalogram (EEG) have been reported in several patients. Standard cytogenetics must be associated with fluorescent in situ hybridization (FISH) analysis, using probes both from proximal chromosome 15 and from the Prader-Willi syndrome/Angelman syndrome (PWS/AS) critical region. Although brain neuroimaging (CT/MRI) is reportedly normal in most idic (15) individuals brain MRI should be performed in all those having seizures, since a malformation of the cerebral cortex may modify prognosis and management. Regular follow-up of the seizure status and pharmacotherapy is essential.