The study tends to survey the effect of duration of auditing tenure on the quality of information uncertainty of business entities. The qualities of information uncertainty are measured via deviation measurements of forecasting EPS, forecasting error of EPS, and variability of stock return. These measurements established in the form of hypotheses are tested by regression of integrated data and generalized least square. The statistical society of this research was nonfinancial corporations in Stock Exchange of Tehran during 2002-2008 (1382-1388). The results of the study of 56 sample corporations showed that there is a significant and reverse relationship between the duration of auditing tenure and the deviation of forecasting EPS and forecasting error of EPS, and there is no significant relationship between the stock return and the duration of auditing tenure. Thus, increasing the duration of auditing tenure tends to decrease uncertainty to provided information by business entities. These findings support the view of auditor expertise and eliminate the concern about viewpoint of auditor independence.