This article discusses the policy of opportunistic maintenance, considering more than one decision criterion by using a multi-attribute value function, for a study developed for a cogeneration system that uses sugarcane bagasse at a power plant in northeastern Brazil, where policy defines what maintenance tasks should be adopted. These policies include minimal repairs, opportunistic maintenance, and preventive maintenance, and availability and cost are addressed based on the preferences of the decision maker. As a result, it was possible to define what the optimum maintenance action should be considering more than one decision criterion and taking into account the preference of the decision maker, from the definition of the decision rule, to determine when the actions of minimal repairs, opportunistic maintenance and preventive maintenance must be performed. (C) 2014 Elsevier Ltd. All rights reserved.