© 2020 Elsevier Inc.Objective: Studies about the relationship between epileptic seizures (ESs) and melatonin are limited in children and have been performed in heterogeneous patient groups and with different methods. In this study, it was planned to investigate this relationship according to seizure and epilepsy characteristics. Material and methods: In 91 children with ES, serum melatonin levels were measured within half an hour following the seizure and on a seizure-free day. Seizures were categorized according to the diagnosis, semiology, etiology, duration, electroencephalography (EEG) findings, and response to treatment. Melatonin levels were compared between each group and control group. In addition, basal melatonin levels of 21 patients with electrical status epilepticus in sleep (ESES) were compared with a control group. Results: Basal melatonin levels were found to be lower in children with ESs and ESES group compared with the control group (p < 0.001, p < 0.001). Likewise, similar results were obtained in subgroups except for remote symptomatic etiology, severe EEG findings, and refractory epilepsy. No significant difference was observed between basal and postseizure levels of melatonin. Conclusion: This is the first study to reveal the relationship between ESs and basal melatonin levels according to all the characteristics of seizure and epilepsy in the largest patient group. It also demonstrates the need for more detailed studies on the role of melatonin in the pathogenesis of both ESs and ESES, which may provide a basis for a future treatment.