Although autopsy studies have documented that heart is affected in most of systemic lupus erythematosus (SLE) patients, clinical manifestations occur in less than 10%. QT dispersion, a new parameter that can be used to assess homogeneity of cardiac repolarization and autonomic function, has not been studied in SLE patients. The aim of our study was to evaluate the QT dispersion (QTd) in SLE patients without overt cardiac involvement. Eighty-three patients with a diagnosis of SLE (mean age 41 +/- 13) and age- and sex-matched 77 healthy control subjects (mean age 43 +/- 10) were enrolled in the study. All subjects had their complete history taken, laboratory examination, and transthoracic echocardiography (ECG). Patients with cardiac disease, hypertension, diabetes, or taking medications that may effect QTd or any ECG abnormalities were excluded. Resting 12-lead ECG were recorded for measurement of QTd. None of the patients and control subjects had overt cardiac involvement. The mean SLE duration was 86.5 +/- 15.4 months. QT dispersion was significantly greater in SLE patients than incontrol subjects (55.2 +/- 24.7 vs 20.7 +/- 5.3 ms, respectively; p < 0.001). There was no correlation between QTd and duration of SLE, SLEDAI-K score, corticosteroid usage, and presence of anti SS-A antibody. QT dispersion is significantly increased in SLE patients without overt cardiac involvement. Our result suggests that prolonged QT dispersion can be a useful noninvasive and simple method for early detection of cardiac involvement in SLE patients.