The article is concerned with significance of learning the theory and mastering methodological means of modern transactional analysis and principle possibility of their implementation in mediation practice. The consistency of transactional analysis basics and mediation principles is shown. The typical complications in mediation process reflected and explained by transactional analysis regularities are revealed and ways to overcome them with the help of its methods are shown. The results of the survey of transactional analysis’ theory and instruments applicability made with participation of practicing mediators are presented. The survey conclusions proved a value of transactional theory and methodology as for increasing productivity of work with parties, as for mediator’s personal and professional growth, first of all for provision of the most significant mediation principle - mediator’s neutrality - abidance.