The principle of equal treatment is one of the fundamental principles of the democratic Rechtsstaat. In administrative law, it is expressed as equal treatment of parties to proceedings that have the same status. This is intended to enhance citizens’ trust in public authorities and decisions they issue. The author presents: the principle of equal treatment in the Polish legal order, enhancing trust in public authorities, the principles of proportionality and impartiality as reflections of equal treatment of participants in administrative proceedings. The analysis is based on the doctrinal and judicature positions.