This article discusses selected issues concerning the exercise by the Sejm of its powers to hold persons performing top State positions (from the point of view of Sejm oversight) accountable before the Tribunal of State. The authors of analysis of the Sejm authority to deal with preliminary motions to hold persons constitutionally accountable pointed out that in such power the oversight function of the Sejm is realized. However, they also noted that such power has at the same time some specific features as compared with other instruments of oversight exercised by Sejm. Then, the proceedings before the Constitutional Accountability Committee of the Sejm were described. In this respect, the standpoint which considers such proceedings as completely consistent with pre-trial proceedings in the penal procedure should be criticized. They also opted for reduction of the scope of the proceedings in the Committee in relation to evidence. Similar criticism was caused by the lack of application by the Committee of instruments regulated in Article 9(2) of the Act on the Tribunal of State. Addressing a controversial issue whether the proceedings to hold persons constitutionally accountable is based on the principle of procedural legality, it was ascertained that in such proceedings the principle of opportunism exists. Therefore, the Sejm is not under legal obligation to initiate, in any case, proceedings in relation to constitutional accountability. Another issue, raised in the article, is admissibility of holding members of collegial bodies constitutionally accountable for actions taken by such body in gremio. As concerns this question, it was stated that individual accountability of members of such bodies for such actions is exceptionally admissible. Finally, the issue of effectiveness of performance by the Sejm of its power to initiate proceedings before the Tribunal of State was discussed. The reasons for low effectiveness in this sphere were indicated.