The activity of the European Court of Human Rights is investigated and the significance of the relevant practice of the European Court for the judicial practice of Ukraine is determined. It is emphasized, that a constitutional complaint serves as an effective means of protecting fundamental human rights, strengthening the rule of law and building democracy, which has already been tested in many countries around the world. The article notes that the institution of constitutional complaint significantly expands the possibilities of protecting citizens. In general, this institution is a kind of constitutional appeal, which should be understood as a written petition, submitted to the Court to review the constitutionality of the law of Ukraine (its constitutional provisions), which is used in the final court decision in the case of the subject of a constitutional rights complaint. The author also draws attention to the issues of advantages and disadvantages of a constitutional complaint and a constitutional appeal separately. Thus, one of the advantages of having a constitutional complaint is that the grounds for filing a constitutional complaint are a violation of fundamental human and civil rights. The advantages also include the fact that, unlike a constitutional appeal, which is a mechanism solely for interpreting a certain provision of the law, which excludes the possibility for individuals to apply to a constitutional justice body to declare regulations unconstitutional, a complaint directly provides such a right. However, at the same time, the model of the constitutional complaint, introduced in Ukraine on the subject, is an incomplete normative constitutional complaint, which is related to the consideration of a specific case. After all, according to it, only one type of normative legal act is subject to appeal, a law, and only the one that was applied during the trial of the person. It is stated, that ensuring the possibility of a person to take an active part in the control over the activities of higher state authorities, which is implemented in the relevant legal forms, provides grounds for recognizing a constitutional complaint as one of the modern institutions of democracy. In fact, a constitutional complaint is an effective procedural means to protect the fundamental rights and freedoms of citizens