There is a general consensus among historians that there was something quite special about the church policy of the Ottonian and Salian rulers of Germany from Henry I to Henry III. The normal reliance of the medieval king on his prelates was here turned into a deliberate and systematic exploitation of the potential of the Church as an instrument of government. These rulers used bishops and abbots, whom they appointed, as a counterweight to a turbulent and unreliable lay nobility. Many historians have, so to speak, followed them in this, have turned from the Ottonians' and Salians' complex and seemingly unsatisfactory relations with their aristocracy to their church policy. Here they have seen plan, system and harmony, so much so that the Church has come to be regarded as the principal instrument of government available to these rulers. Our picture of the Ottonian and Salian ‘imperial church system’, the Reichskirchensystem of German historians, has been much refined by recent scholarship, but the essential outlines have not greatly altered since the time of Waitz and Giesebrecht. The purpose of what follows is to re-examine these outlines. The qualifications, doubts and reinterpretations offered are not all new; many have been expressed or at least hinted at in the existing literature. But they have never been fully articulated, and it seems worth looking again at the Reichskirchensystem as a whole to ask how far in fact it did perform or could have performed the functions usually attributed to it, and to ask also how far it was a system.