In this paper, three versions of a hybrid heuristic algorithm by combining genetic algorithm (GA) and artificial immune system (AIS) is implemented to optimize the multipass turning process which has rough machining and then a finish machining. The objective function considered is minimization of unit production cost that optimizes the machining parameters. The performance of the GA-AIS is evaluated by comparing it with the best performing heuristics reported in the literature. It is observed that the proposed GA-AIS perform better than the heuristics reported in the literature. © 2010 Springer-Verlag.