The story of Johannes Brahms and Breitkopf & Hartel, music publishers of Leipzig, is a story of a chequered relationship. Prophetically introduced and initiated into the publishing world by Robert Schumann, Brahms' pathway to success was practically paved for him. His business association with the tradition-steeped publishing house of Leipzig did not remain unclouded for long, however. The ambitious composer soon found himself confronted with mercantilistic customs that went against his artistic ethos. In addition to describing Brahms' actual relationship with the publishing house, the study also reveals aspects of historical reception such as the general acceptance of Brahms' works in the concert scene in Leipzig and in the music press. This requires a contextualisation of the expanding music publishing business in the 19th century. With the benefit of a new source found recently, the study also focuses on a further topic, namely Brahms' editorial work on four major complete works projects for Breitkopf & Hartel, bringing Brahms' relations with renowned researchers, his knowledge of music history and his music-philological maxims to the fore. German text.