The article is a comparative study of constitutional references to natural law, with a particular emphasis on the Constitution of the Republic of Poland. The findings presented in the study are both of qualitative and quantitative nature. References to natural law, recognized in the constitutions of 48 countries in the world, relate almost exclusively to fundamental human rights and freedoms. Usually, the constitution-maker assigns the title “natural” or “inherent” to all fundamental rights of person or to some of them. In none of the Basic Laws, natural law has been included into formal sources of law, nor its hierarchical relation to positive law shown. No constitution specifies a definite concept of natural law. The authors of the constitutions, speaking generally about natural rights, have not wanted to engage in philosophical and legal disputes accompanying the category of ius naturale.