Information security auditing plays key role in providing any organization’s good security level. Because of the high cost, time and human resource intensiveness, audit expenses optimization becomes an actual issue. One of the solutions could be development of software that allows reducing cost, speeding up and facilitating Information Security audit process. The authors suggest that fuzzy expert systems techniques can offer significant benefits when applied to this area. This paper presents a novel expert systems application, an Expert System in Information Security Audit (ESISA).