Reliability of power systems has been occupying an important measure of system performance and a key factor in system planning, design, and maintenance. The power regime can be divided into three major areas of operation namely, generation, transmission, and distribution. The main duty of distribution system is to deliver an uninterrupted electricity to consumers in changing conditions within accepted levels of cost and reliability. However, it has been found that more than 80% of failures occur in the distribution area. Recently, therefore, many utilities have been concentrating on evaluating and improving their distribution system reliability. This book titled "Reliability Analysis of Power Distribution System" is the first edition and written by Mohammed Wadi. It covers all the fundamentals of probability and statistics required to perform all the reliability analysis and modeling. Besides, it covers the most interruption causes in power distribution, reliability assessments of simple power systems, reliability assessments of complex power systems, reliability assessments of closed-ring power systems, historical reliability assessments.