Das document applies to tangential composite and radia composite inspections on mating gears with cylindrical gears, bevel gears as well as combinations of worms and worm wheels. As a special case of the standard tangential composite inspection, the tangential composite inspection under operating conditions has proved as a suitable means for rating the running and noise properties of gear sets. For the methods stated, the principle of measurement, the measuring instruments, the measurement process and the evaluation of the results are described. It is a common feature of all methods that accumulated deviations are detected which result from the simultaneous effect of the geometrical errors of the two gears during rolling. The different individual deviations thus act summarily on the result of measurement.