The paper presents a method for reliability analysis of composite power systems. The proposed method uses the genetic algorithm (GA) as a state sampling tool. A binary encoded GA is used to represent composite power system network states. The GA uses its fitness function to trace failure states in an intelligent manner. Two approaches for calculating annual and annualized adequacy indices are explained. Sampled states data are saved in a state array. At the end of the sampling process, state array data are used for sensitivity analysis, such as the contribution of different system components to system failure. Case studies on a sample test system are given to explain the effect of a component failure on composite system reliability.