Expert systems are receiving great attentions in construction industry to support decision making processes in diagnostics design repair and rehabilitation of the structures. Although several expert systems have been examined in engineering since the 1970s their applications in construction industry are rare. This was largely due to the lack of expert system tools available to represent the domain knowledge. Lack of flexibility applicability and robustness of the classical models have forced the scientists to discover the ability of the expert systems in problem solving of civil engineering. This paper presents an expert system for diagnosis the deterioration of concrete structures. This expert system emphasizes on cracking distress in reinforced concrete elements. A case study has been presented to examine and evaluate the proposed expert system. The system demonstrates a straightforward method for diagnosing the cause of reinforced concrete elements cracking