Introduction. The issue of the relationship of jus naturalle, that is, as Samuel Pufendorf rightly claims, the same age as the human race and was formed within the framework of ancient Greek law, and Roman law, which is considered the pinnacle of ancient law, is the object of the study in the present article. Currently, many philosophers, lawyers, who try to understand this problem, agree that jus naturalle had a direct and significant impact on the content of Roman law. Purpose. The research is aimed at revealing the relationship between jus naturalle and Roman law and the logical connection between them. Results. To clarify the interaction between jus naturalle and Roman law, the specific characteristics of each system were identified. Theorizing identified with philosophy, the presence of moral attitudes, that are not formalized, in the strict sense, in the documentary legal form, are inherent in natural law. Roman law, on the contrary, is technological, concrete, imperative, not speculative. Both systems appeared in the ancient period, but they did not develop simultaneously, they developed consecutively, with Roman law incorporating the ideas of jus naturalle, which indicates, firstly, their relationship, and, secondly, that jus naturalle was a part of Roman law. This explains the homogeneous relationship between the phenomena under consideration, which is consistently characterized by a number of regularities. Methods of interpretation and legal fictions were widely used to formalize the ideas of jus naturalle into Roman laws. Conclutions. Thus, the Roman law formalized the ideas of jus naturalle in legal regulations, which allowed them to “translate” from abstractions into reality, building the rule of law on their basis.