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Although benign forms of epilepsies with onset in infancy have recently been recognized, the occurrence of seizures in an infant or very young child is very often an event of great significance and the prognosis concerning both epilepsy and neuropsychological development must be guarded. No reliable clinical or electroencephalographic (EEG) markers that can predict the outcome have been described. In a retrospective series of 10 patients, we found a peculiar EEG pattern seen across sleep stages, but not in the waking state in infants whose first seizures appeared before the age of 1 year, and which were mostly complex focal. In all cases, follow-up showed a favourable outcome with complete seizure remission and no cognitive impairment. The specificity of these EEG changes was 100%, but the sensitivity was lower, since they were not seen in some of the infants with the same favourable outcome. We discuss the clinical similarities between our patients and those cases reported earlier by other authors as benign, non-familial or familial focal epilepsies, in whom, however, no interictal abnormalities had been seen on the EEG. Such EEG changes are probably specific to benign, self-limited, early onset focal epilepsies.