The diagnosis of familial Mediterranean fever (FMF) has until recently been based on clinical signs alone. Discovery of the MEFV gene has enabled a molecular approach to diagnosis, which is already well established for diagnosing typical clinical forms of FMF. We evaluated the utility of this molecular approach in a large series of patients with various clinical presentations and ethnic origins. We looked for mutations in the MEFV gene in 303 unselected consecutive patients with a variable (from high to low) clinical suspicion of FMF. Two mutations were found in 133 patients (44%). In 22 patients (7%), the clinical diagnosis of FMF was unlikely according to the Tel Hashomer clinical criteria. Our results suggest that the spectrum of FMF-associated signs is broader than previously believed. Wider indications for genotyping should lead to more frequent diagnosis of FMF.