Introduction: Keeping in mind its relation to arrhythmic risk, we studied the prevalence of long and prolonged QTc interval in men and women with resistant hypertension. Methods: We analyzed the clinical and digital ECG data of 153 ambulatory patients (101 women, mean age 66.94 years and 52 men, mean age 64.92 years) with resistant hypertension. For corerction of QT interval we used the Bazett formula. We defined long QTc > 460 ms in women and > 440 ms men and prolonged QTc > 440 ms in women and > 420 ms in men. Using t-test and chi-square test, we compared the mean values of QTc interval and the prevalence of long and prolonged QTc interval in men and women. Results: The length of mean QTc interval was not statistically diff erent in the two sexes (446 ms vs 445 ms p = 0.1290). Th e prevalence of long and prolonged QTc interval was signifi cantly increased in men (26 men vs 31 women, p = 0.019 and 42 men vs 64 women, p = 0.027). Conclusions: There is a high prevalence of long and prolonged QTc interval in patients with resistant hypertension, especially in men. This fact suggests a reconsideration of the QTc cut-off values in these patients. On the other hand, in planning and monitoring of pharmacological treatment, the higher arrhythmic risk confered by the frequently prolonged QTc interval has to be considered.