This paper aimed to measure the impact of changes in weighted average interest rate on the activities of the Syrian banking industry, which is represented by deposit management and credit policies, and to examine to what extent that activities responds to weighted average interest rate. To achieve the objectives of the study the data has been collected from some Syrian commercial banks during 2005-2010. Two patterns of slight regression have been used, the first to assess the relationship between the weighted average interest rate and deposit indices and the second to examine the relation between deposit indices and credits indices.