Large bandwidth on hand in WDM networks is the best choice for increasing tra c demand; although, routing and wavelength assignment (RWA) problems still remain a challenge. This work proposes a novel method to solve multicast-RWA problems, using multi-objective Particle Swarm Optimization (PSO), implementing four competitive ap- proaches of state-of-the-art. Such algorithms minimize simultaneously the hop count, the number of splitting power light, the number of split- ter node and the balancing of multicast tree for a given set of multicast demands. This way, a set of optimal solutions (known as Pareto set) is obtained in one run of the algorithms, without a priori restrictions. Sim- ulation results prove the viability of the PSO proposal and the advantage compared on classical approaches as Multicast Open Shortest Path First routing algorithm and Least Used wavelength assignment algorithm.