EN
The main aim of the paper was the presentation of the results on the influence of supervisory boards on agency costs reduction in Polish listed companies. The research examines agency theory and helps to evaluate two-tier board model. The sample consisted of 520 observations on 266 non-financial companies listed on the Warsaw Stock Exchange. I had conducted panel data analysis and supported the hypotheses that board structure i.e. percentage of supervisory (non-executive) board members in comparison to management (executive) board members positively affects agency costs reduction measured as selling, general and administrative expense ratio and board size negatively affects agency costs reduction.