The efficient and the economical operation of the power generation units constitutes one of the most important parts of energy engineering. Most of the studies done on this subject have focused on the meeting of the demanded power by the generated power and the minimization of the generation cost of the system. These kinds of problems are the optimization problems in which the total fuel cost is minimized under the system constraints. In this study, economic power dispatch problem with prohibited operating zone which additionally considers ramp-rate limits of the generators as well as the present constraints has been solved by artificial bee colony algorithm (ABC). The transmission line losses used in the solution of the problem have been computed by B-loss matrix. ABC method has been applied to the 15 generator test system in literature. The attained optimum solution values have been compared with the optimum results in literature and the results have been discussed.