Transoesophageal stimulation of the atria combined with bicycle ergometry provides a satisfactory reproducibility of a number of basic electrophysiological parameters at rest and during a load. Due to the good sensitivity and low specificity this test can be recommended in WPW syndrome as a screening examination in particular in active sportsmen and junior subjects. To assess the risk of sudden death in subjects with this syndrome it is, however, necessary to evaluate the complex of all assembled data, as the shortest R-R interval in induced atrial fibrillation is not sufficiently specific.