Febrile seizures are seizures that occur during febrile illnesses in the absence of central nervous system infection or other identifiable aetiology in children who have never had any non-febrile seizures before. Although the condition is quite common, affecting 2–5% of children between 3 months and 5 years of age, the underlying pathomechanism is not fully explained. Immaturity of the nervous system, as well as environmental, genetic and immune factors are contemplated. Viruses are the main aetiological factor of febrile infections accompanied by seizures. The risk of febrile seizures after vaccination is low and may be associated with the child’s genetic predisposition. Deficiency of trace elements, including zinc and iron, may also promote seizures. The association between febrile seizures and vitamin D levels was reported in only few studies. It seems that genetic background plays an important role, at least in some cases. In recent years, particular attention has been paid to the possible involvement of immune factors, including pro- and anti-inflammatory cytokines. Previous studies on the aetiology of febrile seizures confirmed their multifactorial nature and indicated their heterogeneity within this group of patients. Further research may not only contribute to a better understanding of the mechanisms underlying the pathogenesis of febrile seizures, but also determine the direction of actions that may reduce the risk of their occurrence and/or recurrence.