To this day, Joseph Haydn’s symphonies are often performed and recorded in a way that does not meet the composer’s intentions. This concerns certain variants of instrumentation, e.g. the rendering of violoncello obbligato with a single instrument, the use of trumpets and timpani or of horns in high C, respectively. Using the violoncello part of the slow movement of symphony Hob. I:102 as example, it is argued that Haydn in spite of the “solo” mark at the beginning of the movement did not intend the part to be played by one instrument alone. The same applies to most of the passages for violoncello “solo” in his late symphonies. Additionally, it can be established from the sources that before 1768 Haydn did not write for horns in high C and that the parts for trumpets and timpani in some of the early symphonies do not originate with the composer. That these alternatives of instrumentation, though not authentic, have found widespread acceptance in today’s performances is demonstrated by selected recordings from the 1950s to date. A short survey of the history of Haydn’s symphonies on record serves as an introduction to this essay.