The article analyzes the implementation of the principle of equality in the constitutional legal proceedings of Ukraine nowadays. It has been established that this principle is reflected in the decisions of the Constitutional Court of Ukraine: 1) equality of citizens before the law, which does not exclude differentiation of legal regulation, is guaranteed by the prohibition of «negative discrimination» and is not absolute in scope; 2) equality of everyone (i.e. citizens of Ukraine, foreigners, stateless persons) before the court, including equality of all participants of the judicial process; 3) equality of citizens in duties, which means their equal subordination to the laws of Ukraine; 4) equality (equal significance) of rights and freedoms, the manifestation of which is the equality of material and procedural rights, the equality of positive and negative rights. On the basis of the analysis of the decisions of the Constitutional Court of Ukraine, a number of «ontological factors» that determine the principle of equality and are considered methodologically important for legal characterization, have been identified. The first of the proposed factors is the sphere of social life, i.e. the part of the public space that has become «discriminatorily vulnerable», and in light of this the legal positions of the Constitutional Court of Ukraine in respect of the principle of equality in the sphere of realization of electoral rights, labor rights, property rights etc. have been systematized. The second factor can be considered the peculiarities (nature) of legal rights that are «in the area of discriminatory risk», which affects the functions of certain legal means of ensuring equality, in particular, the functions of the so-called legislative qualifications. A third reviewed factor is the relationship between human and civil rights. The dependence of the content and scope of the principle of equality on the joint realization of the right to education and the right to free development of one’s personality; the right to housing and freedom of movement and free choice of place of residence. The fourth factor of the substantive content of the principle of equality is the criteria of differentiation of legal regulation, namely, «appropriateness» (economic, political, social), «justifiability in a democratic society» and «relevance». The fifth factor is associated with the specificity of guarantees of ensuring the principle under consideration, among which — «accessibility», «free-of-charge» basis of education and health care. As the sixth factor, the correlation of the principle of equality with other principles of law, in particular, with the principles of justice, freedom, presumption of innocence and inadmissibility to hold a person responsible for refusing to testify against him/her, has been substantiated. Keywords: rule of law, legal principles, human rights and freedoms, The Constitutional Court of Ukraine, principle of equality.