We study the convergence of the average consensus algorithm in wireless networks in the presence of interference. For regular lattices with periodic boundary conditions, we characterize the convergence properties of optimal MAC protocol that maximizes the speed of convergence on these networks. We provide analytical upper and lower bounds for the convergence rate. Our results show that the fastest converging interconnection topology for the consensus algorithm crucially depends on the geometry of node placement in an interference-limited scenario. © 2008 IEEE.