A maintenance and diagnostic system for a printing machine, preferably a sheet-fed offset printing machine, includes a control system having at least one computer and is connected to signal transmitters that are sensors and/or limit switches. The main drive and other drives of the printing machine are activated via the sensors and/or limit switches. The control system is operatively connected to a control-desk computer containing data on print jobs that are carried out. The control system is arranged to provide a diagnostic and inspection system for printing machines to be used for planning necessary maintenance work in advance to the greatest possible extent such that the downtimes of the printing machine required for maintenance work are minimized. The control system includes a maintenance and inspection computer which is operatively connected to the control system and to the control-desk computer. Signals can be recorded by the control system onto the maintenance and inspection computer. Also, signals sent by the printing machine drives and the signal transmitters are fed to the maintenance and inspection computer. The maintenance and inspection computer uses such signals to determine the condition of consumable materials, and variables representing the stress on and wear of printing machine components provided, and also to determine the times and the extent of appropriate maintenance measures based on such conditions and variables.