In this paper quantitative impact of automatic switches on the reliability of power distribution systems is studied. Based on the characteristics of the studied system's topology, the reliability model is developed for the implementation of Monte Carlo simulation. Reliability indices on each load have been computed to obtain an overall reliability assessment of the system, and the sensitivity of the reliability indices to the location of automatic switches is also studied. Simulation results are used to illustrate the validity of the approach and are compared with the historical reliability records.