Familial Mediterranean fever (FMF) is a disease characterized by sporadic, paroxysmal attacks of fever and serosal inflammation. QT dispersion (QTd) and transmural dispersion of repolarization (TDR), simple noninvasive arrhythmogenic markers, that can be used to assess homogeneity of cardiac repolarization, have not been studied in FMF patients before. The aim of our study was to evaluate the QTd and TDR in FMF patients without overt cardiac involvement. A total of 50 patients with FMF (30 men, 20 women, 29.4 +/- 11.8 years) and 50 controls (30 men, 20 women; mean age 31.3 +/- 11.9 years) were included. QTd, corrected QTd (cQTd), maximum QT (QTmax), maximum corrected QT (cQTmax), minimum QT (QTmin), and minimum corrected QT intervals (cQTmin) and TDR were measured from standard 12-lead electrocardiography (ECG). We found that QTd, QTmax, and TDR were greater in FMF patients than in the control group (36.0 +/- 11.4 vs. 20 +/- 11.2, P < 0.001 and 354.8 +/- 30.9 vs. 342.8 +/- 18.0, P = 0.02; 62.0 +/- 16.0 vs. 49.0 +/- 9.5 P < 0.001, respectively), as were cQTd and cQTmax (40.4 +/- 13.5 vs. 21.9 +/- 12.4, P < 0.001 and 397.7 +/- 40.2 vs. 375.5 +/- 25.4 P = 0.001). A modest positive correlation was found between cQTd and C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) (r = 0.30, P < 0.001; r = 0.40, P < 0.001; respectively). QTd, which is an index of inhomogeneity of ventricular repolarization and an important predictor of cardiovascular mortality, and TDR, which is a better marker of cardiac repolarization, increased in FMF patients similarly as in other rheumatologic diseases.