In this paper, a fuzzy self tuning is designed to update the proportional, integral, and derivative PID (FST-PID) gains which are optimized based on the Ant Colony System ACS. The design procedure is performed through two steps. Firstly, the PID gains are obtained using ACS algorithm and denoted by ACS-PID. Secondly, a fuzzy self-tuning is designed to self tune such gains. The developed approach is applied to the load-frequency control LFC of the Egyptian power system EPS as a single area with multi unit power system. The studied power system comprises three power plants; non-reheat, reheat, and hydro generation plants. The proposed PID controller is designed on an average point of four loading conditions of the EPS during summer and winter of 2008. The effectiveness of the FST-PID controller in the presence of the system inherent nonlinearity generation rate constraint GRC and uncertain system parameters under different disturbances locations are carried out using MATLAB-SIMULINK simulation program. The results prove that the proposed method is very useful in self tuning the PID controller gains for the LFC Egyptian Power System.