This publication is intended to assist managers of nuclear facilities in the adoption of reliability centred maintenance (RCM) programmes in order to optimize operating and maintenance costs. The process of RCM focuses on the functionality of the plant and equipment and on the critical failure mechanism that could result in loss of functionality. An overall RCM process can bring higher levels of reliability and reduce the cost and demands to maximize limited maintenance resources. A number of IAEA Member States currently operate nuclear power plants under an RCM approach; however, others do not because the methodology can be perceived as demanding, complicated and time consuming. Aimed at managers, engineers and plant maintenance specialists, this publication describes the practical RCM methodology and provides examples of successful programme implementation.