The aim of this research is to perform Multi-Objective Optimisation (MOO) study for multistage flashing with brine recirculation and hybrid MSF-RO desalination systems using Genetic Algorithm (GA) technique. The hybrid MSF-RO desalination system has been simulated rigorously using first and second laws of thermodynamics in addition to the plant economical aspects. Four objectives have been considered in this analysis: distillate production, product cost, Gain Ratio and exergy destruction. The desalination systems have been optimised for single, double and triple simultaneous objectives. Results showed that MOO of MSF-BR and hybrid MSF-RO systems were successful and tend to enhance the performance of both systems.