Since the beginning of the Ariane 5 development, space debris mitigation concerns have been taken into account. At system level, the trajectory of the main stage EPC has been constrained in order to avoid a long life time in orbit followed by an uncontrolled reentry. Operational constraints have also been applied to the upper composite in order to avoid payload pollution and collision risks. At stage level, numerous modifications have been implemented, mainly for the various passivation systems: addition of pyrotechnical valves and specific nozzles led to a higher stage complexity. Following the first nine flights of Ariane 5, we now have plenty of data showing how efficient our measures have been.