Clinical-pathological studies have demonstrated that in 46-51% of AIDS patients a lymphocytic interstitial myocarditis can be found at autopsy. In > 80% of these patients no specific etiologic factor for myocarditis was found. This pathological finding is believed to be related to a specific pathogenetic action of HIV on myocardial tissue and it is called HIV-related myocarditis (HRM). In 15-30% of patients with lymphocytic interstitial myocarditis ventricular arrhythmias have been described. In order to assess the prevalence and the predictive value of ventricular ectopic beats (VEB) in the diagnosis of HRM, we performed a retrospective analysis of 24-hour Holter recordings, M-mode and two-dimensional echocardiographic and Doppler parameters and post-mortem myocardial histopathological and virologic findings on a selected sample of 35 NYHA functional class II patients died of AIDS. The patients were divided into two groups according to post-mortem histopathological findings of myocardium specimens: Group 1 (n = 19) including patients with histopathological findings consistent with diagnosis of HRM; Group 2 (n = 16), including patients without histopathological findings of myocarditis. Group 2 patients represented the control group. The retrospective analysis demonstrated a greater prevalence of VEB class IV and subclass IVb in Group 1 compared to Group 2 (p = 0.009 and p = 0.004, respectively). The other classes of VEB did not present a statistically significant difference between groups. VEB class IV presented a 81.2% diagnostic predictive value (subclass IVa: 50%; subclass IVb: 90.9%). Ejection fraction, kinetic score and Doppler E/A ratio, Ei Area, Ai Area and Ai Area/total Area ratio and isovolumetric relaxation time were significantly correlated to Lown's classes of VEB (p < 0.001) and to the values of CD+ cells (p < 0.001); on the other hand, VEB classes correlated significantly with the values of CD+ cells (p < 0.001). Syncytial cells and HIV p24 antigen in cultured myocytes were detected in 17 Group 1 patients (89.4%) and in 2 Group 2 patients (12.5%; p < 0.001). These results have demonstrated that in selected cases of AIDS patients specific classes of VEB may represent a simple and sensitive electrocardiographic marker of HRM. VEB classes correlate significantly with systolic and diastolic echocardiographic parameters and to the values of CD4+ cells. Furthermore, in patients with HRM a direct pathogenetic action of HIV may be assumed.