While analysing constitutions of various countries in the legal literature, typically not only the form and the content but also the structure of the constitution is discussed. The structure of the constitution is an internal organisational order of the norms of the constitution. Although every state’s constitution has a unique structure, certain regularities can be discerned. The analysis of the structure of various constitutions leads to the conclusion that normally each constitution consists of the following standard structural parts: the preamble, the main part, the final, transitional or additional provisions, and in some constitutions there can also be annexes. The article confirms that most constitutions begin with an introductory part, the preamble. Only the constitutions of several countries (e.g. Norway, the Netherlands, Belgium, Italy, Greece) contain no preamble. The preamble reflects the historical context and the circumstances of the adoption of a constitution, names the goals of the constitutional regulation, fortifies the values to be attained, declares the key political principles or even the fundamental human rights and freedoms, etc. Often the preamble reveals the methods of adoption of a constitution. The preamble is an important structural part of the constitution that helps to understand the established constitutional regulation. The principles enshrined in it can be considered a significant argument for the constitutional justice institutions while solving the case of whether the law or any other legal act in question contradicts the constitution. The preamble is not only a political, ideological, and/or philosophical category; it undoubtedly also carries a legal burden, therefore it is considered to have legal validity. Preambles are characterized as having a so-called higher style; they are usually formulated not in compliance with the requirements of legal technique.