The communication industry was passing in lastest years by great transformations in world. Internet is the mainly responsable for that, because there is the necessity of a large band to data transmission. The optical networks concept and wavelength division multiplexing technology were arised in order to solve this problem. However, this created another problem: the packet routing. The major part of communications networks still has electronics signals. This means that the optical signals have to be converted into electrical signals to be amplified, regenerated and routed and later recovered into optical. This implies in a delay on the data transmission and creates a bottleneck in the optical networks. Some algorithms have been created to minimize this problem. This dissertation has tried to develop an algorithm to solve RWA (routing and wavelength assignment) problems, aiming at the minimum total cost to transmitt datas. This algorithm was tested and compared with the linear program algorithm that gives the optimal solution to RWA problem.