Decision making is a fundamental tool for managers and enable them to make logical decisions in critical situation between different options. This thesis concentrates mainly on seller selection problem or in some cases it also refers to vendor or supplier selection problem (SSP) and demonstrates how the multiple attribute decision making (MADM) methods can be effectively used for vendor selection decision in various situations of project management and supply chain environment. A case study has been carried out within two different countries (Sweden and Iran) in order to help practically managers to choose the best alternatives among their preferences. In this regard, AHP as one of major tools of MADM is also deployed.