In this paper, we investigate the investment portfolios determinants using a sample of Greek and Polish private investors. The study is grounded in the current and potential criteria and sub-criteria influencing investors in selecting financial investment products. The methodology applied in order to satisfy the research aims is the Analytic Hierarchy Process (AHP). This is a flexible and functional tool for investigating multi-criteria decision-making problems that allows the determination, evaluation, and comparison of major criteria by stakeholders. The results show that there are considerable differences in the ranking and significance of factors that determine the selection of financial investment products in these two countries. The importance of those factors has implications for the decision-makers in the banking sector.