To assess the clinical characteristics of patients living in France and carrying a single MEFV mutation.A retrospective chart review of patients referred to us for recurrent fevers. Genetic testing: systematic screening of exons 2 and 10 was performed in the MEFV gene. A subset of patients was also investigated for other auto-inflammatory genes.We analysed 94 patients (sex ratio:1). Forty-two percent of them were Jews and 17% were Arabs. The median age of onset was 2 years (3 months-47 years). Fever was >39 degrees C in 80% of them, while the duration and frequency of an attack varied (3 days: 36%; >2 months: 15%; 1-2 months: 48%; and <1 month: 37%, respectively). Peritonitis occurred in 97%, pleuritis in 25%, arthralgia in 53%; skin rashes in 20%, aphthosis in 18% and lymphadenopathy in 9%. MEFV mutations were M694V (60%) and M694I (7%). The R92Q TRAPS mutation was retrieved in 3/21 patients tested and the V377I MKD mutation in 1/6. Associated diseases in these patients were periodic fever, aphthosis pharyngitis and adenitis syndrome (4), AS (5), Crohn's disease (2) and Castleman's disease (1).The clinical picture of French heterozygote patients with recurrent fevers resembles that of homozygote patients. Most of them required colchicine treatment.