Ignoring the delicacy of risk management in IT projects, not only is a cause that goals are not achieved, but may lead to project failure. Meanwhile identifying the most important factors affecting risks of IT projects and assessing their relationships play an essential role in management decisions. The purpose of this paper is to identify and assess the relations between factors affecting risk of Mellat Bank IT Projects in Bushehr province using fuzzy decision-making trial and evaluation laboratory )DEMATEL( techniques. For the same reason we studied the most available literature on the issue and identified 23 major factors and found the importance of each one from the viewpoint of experts. By this, 8 factors which are most influential were identified and then the second questionnaire was developed for applying fuzzy DEMATEL method and was issued to a group of 15 chosen experts to find the causal relation among these eight factors and to find the most important factors affect on implementing Mellat Bank IT Projects in Bushehr province. The results show that unskillful employees and lack of knowledge in human resources, resource monopoly, lack of reliability in data storage, and absence of a control system in implementing an IT project are the most factors affecting risk of Mellat Bank IT Projects in Bushehr province.