Objective: The aim of this study was to assess the factors that cause delay in diagnosis of familial Mediterranean fever (FMF), which is a common disease in our country. Material and Methods: The data of 101 patients diagnosed with FMF in our pediatric rheumatology center between 2010 and 2021 were retrospectively analyzed. The time elapsed from the onset of the patients' symptoms to the time of diagnosis was defined as the delay in diagnosis. Pras disease severity score was used to determine disease severity. Results: Fifty-nine of 101 patients were girls (58.4%). The median age at onset of symptoms was 5 (min-max: 2-8) years. The median age at diagnosis of the patients was 6 (min-max: 4-9) years. Delay in diagnosis was <1 year in 41 patients, <1-3 years in 40 patients, and >3 years in 20 patients. There were 39 (38.6%) M694V homozygous, 34 (33.7%) M694V heterozygous, 13 (12.9%) non-M694V mutations, 2 (2%) patients with a single mutation except M694V, and 13 (%13) patients with no mutation. According to the Pras disease severity score, disease severity was classified as mild in 22.8%, moderate in 43.6%, and severe in 33.7% of the patients. There was no relationship between family history of FMF, consanguineous marriage, clinical findings, mutations, and delay in diagnosis. A statistically significant relationship was found between the delay in diagnosis of more than 3 years and the age of onset of symptoms of the patients (p<0.001). A statistically significant correlation was observed between mild disease and delay in diagnosis of more than 3 years according to Pras disease severity score (p=0.026). Conclusion: Diagnosis of FMF may be delayed if symptoms begin in infancy and are compatible with mild disease. FMF should be kept in mind in children with symptoms such as recurrent fever and abdominal pain in early childhood.