This article deals with certain theories of legal norm structure. The author is observing the evolutionary change in Czechoslovakian legal theory which was determined by Soviet legal theory. Before the year 1948 some authors were explaining the structure of legal norm as consisting of two elements (legal condition and legal consequence). This has changed after 1948 as our legal theorists were inspired by Soviet invention – a three-element structure of legal norm (hypothesis, disposition and sanction). Though this theory was later heavily criticized and replaced by a construction called duplicate structure of legal norm, it is still regarded by some current Slovak and Czech law professors. This paper tries to find an incontrovertible theory of legal norm structure. A good starting point according to the author is invention of deontic logic, especially in works of G. H. von Wright, which is a challenge for explanations included in legal theory textbooks in Slovakia and Czech Republic. In conclusion the author asserts to realize a revision of used terminology, to make it comprehensible also with reference to traditional terminology of a two-element structure of legal norm which is considered by him as the most appropriate explication.