AbstractModern manufacturing systems are characterized by an increasing complexity and high dynamic. This leads to new challenges for the operational planning of maintenance and production. This paper introduces a novel approach to an online simulation which enables a cost-optimized integration of condition-based maintenance measures in the production plan. The dynamic approach is implemented by means of event-driven simulation. It enables to depict the actual state of a complex manufacturing system, to simulate the future development of the production and thereby to evaluate different planning alternatives of maintenance