Objective: There are a handful of studies investigating peri-ictal headache (PIH) and its clinical associa-tions in patients with idiopathic/genetic epilepsies (I/GE). This multi-center study aimed to investigate PIH, which is an ignored comorbid condition in patients with I/GE, by headache experts and epileptolo-gists working together.Methods: The data were collected from a cross-sectional large study, using two structured questionnaires for headache and epilepsy features, fulfilled by neurologists. Headaches were classified according to the International Classification of Headache Disorders, third edition, whereas seizure and syndrome types were diagnosed according to International League Against Epilepsy criteria. The patients with a headache starting 24 hours before the onset of the seizure (preictal) or within 3 hours after the seizure (postictal) were defined as patients with PIH. We compared demographic and clinical differences between two groups of patients with and without PIH statistically and used ROC curves to determine a threshold of the total number of seizure triggers associated with the occurrence of PIH.Results: Among 809 (531 females, 65.6%) consecutive patients with I/GE, 105 (13%) patients reported PIH (22 preictal, 82 postictal headaches, and one with both types). Peri-ictal headache was more frequently reported by females and those having a family history of migraine or epilepsy, and it was significantly associated with lower rates of seizure freedom for more than five years, drug resistance, and use of poly -therapy, remarkably. Moreover, ROC curves showed that having more than 3 seizure triggers was asso-ciated with the presence of PIH.Conclusion: Our findings revealed that PIH may be linked to poor outcomes in I/GEs and seems to be related to a lower ictal threshold precipitated by multiple triggers. Future prospective studies will illumi-nate the unknown underlying mechanisms and appropriate management strategies for PIH to improve the prognosis.(c) 2023 Elsevier Inc. All rights reserved.