The article is theoretical, its aim is to bring closer the problem of the impostor syndrome/ phenomenon (IP) which is not yet well known in Poland. The impostor phenomenon means the sense of intellectual falseness that exists among people who experience a discrepancy between their own attitude towards their achievements and the evaluation of these achievements by other people. According to external criteria, persons with impostor phenomenon are seen as being successful, but according to their own internalized standards, they perceive their accomplishments as not significant. They contribute them to good fortune, lucky chance or beneficial contacts. A study conducted by the authors of this article shows that the impostor phenomenon can be observed also in Poland. Precise information on this research project will be presented in other publications. The aim of this article is to introduce into the problem and to illustrate it by short clinical vignettes. The analysis of the characteristics of the impostor phenomenon can be of importance for deepening the understanding of the problems of patients participating in psychotherapy.