Background: Cardiac arrhythmias can be a part of cardiovascular involvement in some rheumatic diseases, but data about familial Mediterranean fever (FMF) are conflicting. Aim: To search for abnormalities in ventricular repolarization indices in FMF patients. Patients and methods: Seventy seven FMF patients and 30 age/gender comparable healthy controls were included. All patients were attack free and subjects with disease or drugs that are known to alter cardiac electrophysiology were excluded. Electrocardiographic data were obtained and analyzed. Results: Twelve FMF patients had amyloidosis. QT and QTc intervals were within the normal ranges and similar between FMF patients and healthy controls. QT dispersion, peak to end interval of T wave (Tpe), Tpe/QT and Tpe/QTc ratios were significantly higher in FMF patients than in healthy controls. Patients with amyloidosis had significantly higher QT dispersion, Tpe, Tpe/QT and Tpe/QTc than their counterparts without FMF. Levels of proteinuria were moderately correlated with QT dispersion, Tpe, Tpe/QT and Tpe/QTc. Conclusions: FMF patients may have an increased risk for arrhythmias. ?