T wave alternans (TWA) is a reliable marker of risk for malignant ventricular arrhythmias whose prognosis value has been established in many populations. Short QT syndrome (SQTS) is a recently described and very rare channelopathy defined by a decrease in repolarisation duration and carrying a risk of ventricular fibrillation. TWA in SQTS has not been evaluated at yet. 6 patients with SQTS (QT 310 ± 16 ms, QTc 329 ± 11 ms) underwent microvolt TWA measurement using spectral analysis. TWA testing was performed using Heartwave II (Cambridge Heart TM ) during bicycle exercice and classified as negative, positive or indeterminate according to the published standards for clinical interpretation. there were 6 men (mean age 24 ± 2 yo): 4 asymptomatic, 1 with previous sudden cardiac death and 1 with unexplained syncope. 3 patients belonged from the same family. Familial history of SQTS was present in 4 (2 families) and history of unexplained sudden death was found in both families. Ventricular fibrillation was induced in 2 of 5 investigated patients. Two patients were implanted with an ICD without any appropriate therapy during follow-up. No patient was on any medical therapy. Genetic analysis was pending in each but without result at yet. TWA was negative in each patient except in one inducible asymptomatic patient (indeterminate due to too fast heart rate). Maximal negative heart rate was 113 ± 5 bpm. Conversely to what is observed in other settings, TWA testing is negative in most SQTS patients even in the symptomatic or inducible ones. This may be explained by the longer diastolic interval according to the restitution curve theory. Measurement of TWA for risk stratification in SQTS is therefore useless.