In this study, a fuzzy gain scheduled proportional and integral (FGPI) controller was developed to regulate and to improve the frequency deviation in a two-area electrical interconnected power system. Also, a conventional integral (I), a conventional proportional and integral (PI), and a fuzzy logic (FL), controllers were used to control the same power system for the performance comparison. Two performance criteria were utulized for the comparison. First, settling times and overshoots of the frequency deviation were compared. Later, the absolute error integral analysis method was calculated to compare all the controllers. All the models were simulated by Matlab 6.0-Simulink software. The simulation results show that the FGPI controller developed in this study performs better than the other controllers with respect to the settling time and overshoot, and absolute error integral of the frequency deviation. (C) 2004 Elsevier B.V. All rights reserved.