In this paper, an improvement of sliding mode control design is investigated. A fast reaching velocity into the switching hyperplane in the hitting phase and little chattering phenomena in the sliding phase is desired. A fuzzy sliding mode control (FSMC) in cooperation with genetic algorithms (GAs) in coupled tanks problem is studied. A fuzzy logic controller is used to replace the discontinuity in the signoum function of the reaching law in the sliding mode control (SMC). Parameters of FSMC are adjusted by GAs. Finally, the performance and the significance of the controlled system are investigated under variation in system parameters and also in presence of an external disturbance. The simulation results indicate performance of genetic-based FSMC controller.