The relationship between orthodox or mainstream medicine and heterodox or alternative practices has often been expressed in terms of dichotomies, such as science versus anti-science or rationality versus irrationality. By studying the history of a company producing herbal medicines and homoepathic remedies in Germany in the 1920s and 1930s, this paper attempts to create a more differentiated picture. 'Dr. Madaus & Co.' was founded in 1919 by the three sons of a free church minister and his wife, who practised as a non-licensed healer herself. The company not only sold medicines, it also produced journals and books promoting heterodox healing methods and contributing to ongoing health political debates, for example over compulsory vaccination programmes, human experimentation, quackery, and a general 'crisis of medicine'. Gerhard Madaus, a medical doctor and one of the three founders, published in 1938 a three-volume Textbook of Biological Healing Methods, turning folk medicine into science. The essay follows the rise of the Madaus family firm and interprets the story of 'Dr. Madaus & Co.' as an example of social rationalization, emphasizing the role of commercial operations in twentieth-century alternative medicine in Germany.