Recently, a new set of criteria was established for the diagnosis of familial Mediterranean fever (FMF) in childhood. The aim of this study is to validate the new criteria set among heterozygous patients with clinical features of FMF. The study group consisted of FMF patients, who had a mutation at a single allele, who were followed in four pediatric nephrology-rheumatology centers in Turkey. Patients were evaluated by the new criteria set and also by the Tel Hashomer criteria. According to the new criteria, the diagnosis of FMF was established by the presence of two or more of five criteria (fever, abdominal pain, chest pain, arthritis, family history of FMF). The study group consisted of 110 FMF (54 male, 56 female) patients. Majority of the patients had heterozygous pM694V mutation (65%). The sensitivity of the new criteria set and that of the Tel Hashomer criteria in our study group were found to be 93% and 100%, respectively. In conclusion, this study designates that sensitivity of the new criteria set is also high in patients who had a mutation at a single allele.