The increase in fossil fuel prices has resulted in growing utilization of renewable energy sources in power systems. Wind energy as an economical source of energy has experienced the fastest growth among other energy sources. Traditionally, renewable energy sources as a result of their random nature have not been considered in the process of generation expansion planning. The increase in fossil fuel prices and their scarcity in the near future necessitate incorporating wind power in generation expansion planning. This paper studies the utilization of wind power in generation planning considering reliability constraints. Simulation results show that even though wind energy may make a major contribution to generation capacity planning, reliability limitations hinder full utilization of potential wind power. Therefore, conventional generating units should still be taken into account in generation planning while satisfying system reliability criteria.