The relationship between QT duration and its dispersion in patients with primary hyperaldosteronism is not clearly known. We studied 26 patients (nine males and 17 females) with primary hyperaldosteronism. The serum potassium levels were low (2.32 +/- 0.52 mmol/l), did not correlate with serum renin or aldosterone levels, or aldosterone/renin ratio (ARR). The maximum QT intervals (QTmax) were prolonged (502 +/- 62 ms), correlated well with ARRs (p = 0.005) and aldosterone levels (p = 0.019), but not to renin (p = 0.517) or potassium levels (p = 0.196). The QT dispersions (QTd) were small (60 +/- 28.8 ms) and did not correlate with potassium, renin or aldosterone levels. QTmax but not QTd correlate with aldosterone levels in patients with primary aldosteronism. The maintenance of repolarisation homogeneity with relatively unchanged QT dispersion may contribute to our understanding of the clinical observation that ventricular tachydysrhythmia is rare among patients with primary aldosteronism.