IT governance implies a system in which all stakeholders, including the board, internal customers and related areas such as finance, have the necessary input into the decision making process. IT governance is the preparation for, making of and implementation of IT-related decisions regarding goals, processes, people and technology on a tactical or strategic level. But, the concepts of IT governance are broad and ambiguous which in turn implicate difficult and inaccurate assessments. In particular, the traditional handling of IT management by board-level executives is that due to limited technical experience and IT complexity, key decisions are deferred to IT professionals. This paper presents a fuzzy reasoning model for assessing IT governance complexity based on an extensive literature study. This model can be used for a good understanding how the concerns of IT governance behave, how they interact and form the behaviour of the whole system. The model for assessing IT governance is employed to compare how IT governance is defined in practitioners and Cobit.