This paper presents results obtained by a combined genetic algorithm and random mutation hill climbing technique called GA-RMHC, applied to solve a formulation for the shortterm transmission expansion planning problem. In this methodology, the overall problem is subdivided in an investment and in an operation sub-problem, which are solved in a successive and iterative way. In the first sub-problem, a GA-RMHC is used to choose the values of the expansion variables (new lines, capacitors, etc.). In the second sub-problem, simulations are performed to decide whether the system variables in the expanded electrical system satisfy the operational constraints. The results were obtained for the Garver's system. © 2009 IEEE.