© Springer Nature Singapore Pte Ltd. 2017. Lead (Pb++) is a toxic agent that can exert adverse effects on the cardiac human health. Pb++blocks the Ltype Ca++channels. A decrease in L-type calcium current (ICaL) is an important mechanism favoring atrial fibrillation. It is important to study the electrophysiological Pb++effects on the atrial action potential in healthy people and those with AF. For this, we study the consequences of Pb++on action potential, under normal and atrial fibrillation condition using in silico models. Our results suggest that Pb++blocks ICaLcurrent in a fraction greater as the concentration increases, resulting in an action potential duration shortening, Pb++has a greater action potential duration effect on control conditions. To our knowledge, this is the first work that has developed mathematical models of Pb++effect on ICaLcurrent to study its effect on human atrial action potential.