Aim: The question of why some children are more susceptible to febrile seizures(FS) is a subject of research. Familial Mediterranean fever(FMF) and periodic fever, aphthous stomatitis, pharyngitis and adenitis(PFAPA) syndrome are the two most common autoinflammatory diseases characterized by frequent episodes with high fevers. We aimed to identifythe predictors of FS in patients with FMF andPFAPA. Material and Method: A total of 112 patients, 66 patients with PFAPA and 46 patients with FMF, whose symptoms' onset was before six years of age, were enrolled between January 2015 and January 2018 in our tertiary hospital. Regression analysis was used to assess the risk factors. Results: Family history of recurrent febrile tonsillitis was found to be one of the predictors of FS(P = 0.038) in PFAPA syndrome and was observed in 31.8%(22/67) of patients. The risk of FS was not different between patients with and without MEFV variants in PFAPA syndrome. The frequency and recurrence rate of FS was 18.2% and 58.3% in PFAPA syndrome, and 15.2% and 57.1% in FMF. Patients with family history of recurrent fever had 3.4 times higher odds of having FS(p=0.019)(95% CI=1.2 to 9.5). Frequency of fever was not found as a predictor of FS, although duration of fever was a predictor of FS. Family history of recurrent fever was not correlated with the family history of FS. Discussion: It may be suggested that susceptibility of FS in patients with FMF and PFAPA syndrome may not be attributable solely to the characteristic features of fever.