Recently, electrical energy consumption has been increasing significantly as a consequence of industry advancement and lifestyle quality improvement. To fulfill future energy demand, the generation capacity has to be expanded. Previously, power generation was essentially based on conventional units. But, because of some issues related to the environment and economy, the permeation of renewable energy (RE) resources in the electrical power system have been notably increased bringing significant challenges to transmission expansion planning (TEP) issue due to intermittent and unmanageable nature of the renewable resources. TEP is a mixed integer non-linear optimization problem. Where its essential aim is to determine the optimum lines to be constructed in order to transmit the power and supply the current and the predicted load in a reliable and economical way over the planning horizon. This thesis proposes a methodology for solving the TEP problem with consideration of wind farms integration into the power system. Where a hybrid heuristic optimization approach (a mixture of backward and forward approach) is utilized to find the optimum branches to be built for several scenarios of wind energy generation to show the impact of the RE resources on the TEP. Moreover, both conditions normal and N-1 contingency are considered to ensure the robustness of the system against the contingencies and check if it is able to withstand at least one contingency criterion. iv The proposed approach was applied to the 24-Bus IEEE Reliability Test System where the optimal solutions of the different cases were obtained and the results confirmed that penetration of wind farm does modify the optimal plan. Keywords: Transmission expansion planning, renewable energy resources, wind farms, forecasted load, uncertainty, IEEE-RTS, contingency N-1, optimization techniques, hybrid approach