This paper presents a newmethod to allocate the costs of the transmission system among generators and loads. The allocation is calculated for each branch of the transmission system to identify and quantify the individual responsibility of generators and loads. A two-step method based on the perfect coupling of the circuit theory with the Aumann-Shapley method is proposed here. First: to determine the participation of the generators in the costs of the transmission network, the generators aremodeled as current injections and the loads as impedances. Second: to determine the participation of the loads in the cost of the transmission network, the loads are modeled as current sources and the generators as impedances. The Aumann-Shapley method and the circuit theory are used to calculate the participation of each real and imaginary current component in the "Allocation of the costs of the transmission system" game by considering them as independent agents. The properties of the Aumann-Shapley method ensure equitable allocation and recovery of the total costs. Numerical results are presented and discussed to demonstrate the applicability of the proposed method. © 2013 IEEE.