A global search algorithm is presented for topology optimization of trusses based on the genetic algorithm. The nodal cost, as well as the member cost, is incorporated in the cost function. A topological bit is introduced to indicate the existence of each member. It is shown, based on the schemata theorem, that the use of the topological bit leads to rapid convergence of the solution to an optimal topology with small number of members. The efficiency of the proposed method is demonstrated in the examples of plane trusses and the effect of the nodal cost on optimal topologies is discussed.