Background The term epileptiform discharge typically refers to interictal paroxysmal activity that occurs more commonly during sleep. This type of paroxysmal activity does not include the electroencephalographic (EEG) activity observed during a seizure. The prevalence of epileptiform activity in the general pediatric population is unknown. Methods Polysomnographic (PSG) studies were conducted in otherwise healthy children recruited from the general population and with no previous history of seizures or any other medical conditions. All sleep studies included an eight-lead EEG montage. Spike and sharp waves, either alone or accompanied by slow waves, occurring singly or in bursts lasting <5s were considered as representing epileptiform activity. Results Nine hundred seventy children underwent overnight PSG. In 14 children, evidence of epileptiform activity, in the absence of any additional abnormality in the PSG, occurred. Thus, the prevalence of epileptiform activity was 1.45%. Epileptiform patterns found were either spike or spike and wave and were more prominent during non-rapid eye movement (NREM) sleep, with 11 patients presenting spike and spike and wave patterns in the centro-temporal regions. Four of the six children who underwent neurocognitive tests exhibited abnormal findings in areas of behavior, attention, hyperactivity, and learning. Conclusion Epileptiform activity in otherwise healthy children from the community is relatively frequent and, if confirmed by prospective studies, could be associated with suboptimal cognitive and behavioral functions. Increased awareness by sleep professionals and use of PSG montage that includes temporal leads and >2 standard EEG leads should facilitate the detection of epileptiform activity in children.