Many studies on the office market have been conducted for the last thirty years. Especially variables which are expected to affect office rents were examined for different cities. The extent of variables was used in these studies reflecting variations in locational and/or economical conditions of the different cities.It is aimed to examine the development of the Istanbul office market in the last decade from the perspective of brokerage firms. The perception of brokerage firms on the effectiveness of these academically defined variables is important. First, it will provide some evidence on whether or not the reported influences of these variables remain the same in the Istanbul office market. Second, it may define how well practitioners’ criteria fit academically defined variables during the decision-making process for a new office investment.The study derives the currently well established locational, building, econometric and contract variables from previously published studies. Based on the result of a survey study administrated to the leading real estate brokerage firms in Istanbul, it will be revealed how Istanbul office market changed in the last decade compared to the reported results from the previous study (Oven and Pekdemir, 2004). Istanbul office market experienced two major crisis in 2001 and 2008, former Turkish banking crisis and later global financial crisis. The market behaviour will be examined from the perspective of the brokerage firms.