The subject of the article was to discuss the institutions of presumptions and legal fictions applicable in the general administrative procedure. Due to the complexity of the problem, the author has attempted to only analyse selected issues relating to the subject matter hereof. The study identifies situations in which the discussed institutions are established, describes their substance, function and the objective for which they were introduced. The impact presumptions and legal fictions on the validity of objective truth in the course of administrative proceedings have been demonstrated and the values underlying their introduction to the Code of Administrative Procedure have been discussed.Przedmiotem artykułu było omówienie instytucji do...