The Investment of important banking service that characterizes the popular credit bank from other public and private banks from other public and private banks, certificates, also serves the interest rate imposed on it by the council of monetary and credit significant role in the economic structure or the society. Accordingly, the order intake find the mist important ideas that serve the research topic, according to the following: 1-The general concept of the interest rate. 2-The general concept of investment certificates and types. 3-Impact of validity in interest rates on the sales and redemptions of investment certificates in the popular credit bank. We have using annual data for the variables of the study with in the period (2004 -2012) in the popular credit bank.