The article discusses the factors influencing the demand for money in the Iranian economy from 1989 to 2000. It highlights the importance of transaction demand for money and the opportunity cost of holding money. The study points out errors in previous research, such as including incorrect factors in the demand for money model, leading to inaccurate calculations of budget deficits. Additionally, mistakes in data conversion and the use of stationary variables in regression analysis have resulted in incorrect coefficient estimates. Overall, previous studies have failed to provide a clear interpretation of money income elasticity.