The authors report on their experience in investigating late potentials (LPs) in arrhythmogenic right ventricular dysplasia (ARVD), by comparing 35 patients with ARVD with 40 control subjects. The values of QRS and RMS40 and the duration of the LP showed a marked difference between the control group and the ARVDs, particularly if sustained VT was present. In this case, 68 per cent of patients were found to have LPs (with at least 2 out of 3 parameters abnormal) versus 50 per cent in the ARVDs without sustained VT and 5 per cent in the controls. There was a difference between the diffuse forms (10 per cent) and the localized forms (25 per cent) of ARVD: the LPs were markedly more obvious in the diffuse forms. Likewise, there was a clear relationship between age and the criteria for LPs in ARVD with sustained VT. This is an argument in favour of the evolutive character of the disease, which could be observed directly in a few cases in which the examinations were repeated over the course of time.