The research aims to measure the size of the accounting reservation in the Iraqi private banks, practices, and concentration on the performance of banks through their performance is evaluated using the Tobin measure's Q, where the research community Iraqi banks listed on the Iraq Stock Exchange amounting to twenty-three banks during the time series stretching from 2010 to in 2014, the research sample was fourteen banks or approximately 60% of the research community, and the results also showed a discrepancy between the banks and the research sample in the accounting reservation practices based on the measure of book value to market value, where the results indicated the practice of some banks to keep the accounting in time who did not have some of the other practices of the policies of conservative enough, and the researcher recommends the banks that follow conservative practices not to abandon the application of those practices while striving to achieve a balance between high market value and the book value, as the rising market value means the Bank's performance evaluation in a positive and reflects the efficiency of the performance, either high book value increase means the accounting practices of the reservation, which requires the application so as to provide more appropriate information for decision-making and increases the value of the bank.