Background Benign childhood epilepsy with centrotemporal spikes is benign childhood epilepsy, presenting between 4 and 10 years of age, characterized by typical clinical and EEG findings. Despite excellent prognosis, there are reports of mild cognitive, language, fine motor and behavioral difficulties. In its atypical form – electrical status epilepticus during slow wave sleep, continuous epileptiform activity during sleep lead to severe neurocognitive deterioration. Our objective was to investigate the influence of abundant sleep epileptiform activity, not fulfilling the criteria for electrical status epilepticus during Slow Wave Sleep, discovered randomly in children without overt intellectual impairment. Methods We retrospectively reviewed the charts and EEG's of 34 children with benign childhood epilepsy with centrotemporal spikes, who underwent neurocognitive evaluation. The neurocognitive battery included items in the following domains: attention span, memory, language, fine motor and behavior. Patients were divided into two groups according to the spike wave index on sleep EEG, with a cut-off point of 50%. The groups were compared regarding to neurocognitive performance. Outcomes Children with epileptiform activity of more than 50%, were diagnosed at a significantly younger age (5.13 ± 1.94 years vs. 7.17 ± 2.45, p = 0.014 T test), had less controlled seizures and received more antiepileptic drugs. However, there was no difference in neurocognitive performance, except in fine motor tasks (Pegboard), where children with more abundant activity were scored lower (−0.79 ± 0.96 vs. 0.20 ± 1.05, p = 0.011, T test). Conclusion Our study did not show negative cognitive effect of abundant epileptiform activity discovered randomly in children with benign childhood epilepsy with centrotemporal spikes, warranting aggressive treatment.