Introduction. At the beginning of the 20th century, the theory of social hygiene was widely recognized worldwide. This science’s birthplace is Germany, and its founder is Alfred Grotjahn. In 1904, he presented a scientific concept of social hygiene, including a new hygienic science, field of study, subject, methodology, and scientific methods. Purpose. This study examines the scientific approaches to social hygiene in German academic literature from the early 1900s to the late 1920s. Materials and methods. This study gathered the necessary data by comprehensively reviewing key German manuals and periodic annual compilations. Results. A. Grotjahn viewed social hygiene as a science combining descriptive and normative approaches. By social hygiene, he meant the study of conditions affecting the social hygiene culture of individuals about place, time, and social environment, as well as their offspring. The descriptive component of the science aims to analyze these conditions, while the normative side investigates measures to improve hygienic culture among individuals and their offspring. He proposed to apply the probability theory as a scientific methodology and utilized the scientific methods of statistics, economics, history, sociology, and politics. Until the 1920s, German social hygienists followed Grotjahn’s theory in their manuals. In the mid-1920s, Ferdinand Huppe introduced the concept of constitutional hygiene theory in a multi-volume handbook of social hygiene. It was based on the methods of biology and the principles of racial hygiene. Conclusion. Grotjahn’s scientific concept of social hygiene underwent significant changes and evolution in the early twentieth century. These transformations, which were influenced by introducing new theories and applying different scientific methods, are crucial to understanding the development of social hygiene as a discipline.