This paper addresses the problem of designing optimum, i.e. efficient and effective, maintenance concepts. The maintenance concept is defined here as the set of maintenance interventions of various types (corrective, preventive, condition-based, opportunistic, design-based, ...) and the general structure in which these interventions are foreseen. The latter is not an easy task, especially not when complex equipment with a high level of automation is involved or when the equipment in question is rather new and not much data is available yet. This paper reports on a critical literature study on the subject. In the evaluation the practical applicability of the methods and the decision support mechanisms were considered to be very important. Developing a maintenance concept for an automated spraying installation tested the practical applicability of such a concept.