Among a series of 98 newborns who experienced neonatal seizures, 20 of them were individualized for they illustrated a "new syndrome": "the seizures of the fifth day of life". These patients were born at term, their maternal and natal history was unremarkable. Seizures always began around the fifth day and most often constituted a real electro-clinical état de mal. EEG reveals alternating sharpened theta waves, a pattern which seems to be characteristic. Some 6 days later, children recovered completely. Further evolution appeared to be always favorable. Although etiological enquiry remained negative, many facts suggested a viral etiology. This syndrome is probably frequent as it was also observed in other neonatal units.