Mobile Ad Hoc Networks (MANETS) are infrastructureless network consisting of mobile nodes, with constantly changing topologies, that communicate via a wireless medium. Therefore, routing is a challenging issue in MANETs. Recently, nature inspired algorithms have been explored as means of finding an efficient solution to this routing problem. In this paper, we develop an improved routing algorithm for MANETs based on Ant Colony Optimization (ACO) inspired by real ants. The performance of the??routing algorithm is evaluated through simulation and is compared to an existing well known MANET routing protocol, Ad hoc On-Demand Distance Vector (AODV). Several performance metrics are considered in different scenarios with varying mobility levels and traffic load.