The arrhythmogenicity of anti-Ro/SSA antibodies for the foetal heart and their crucial role in the development of congenital heart block is now well established, representing a paradigmatic model of passively acquired autoimmunity. Recently, intriguing data suggest that also the adult heart may represent a possible target of anti-Ro/SSA antibody-mediated autoimmune injury. The prolongation of the QTc interval, possibly resulting from a direct inhibitory interaction between the anti-Ro/SSA antibodies and the potassium current I(Kr) in the heart seems the abnormality more frequently observed in adults with anti-Ro/SSA-positive CTD. Although the possibility that anti-Ro/SSA positivity may be considered a risk factor for arrhythmic sudden death in adults has not been demonstrated as yet, preliminary data suggest a relationship among anti-Ro/SSA antibodies, QTc prolongation, and the prevalence of ventricular arrhythmias, also life threatening, in adult patients.