Business Process Management combines a vision focused on processes and a functionalities integration view to enhance an organization's effectiveness. It provides ways to implement the processes and provides functionalities to control and modify their workflows. A very useful tool to achieve this control is a set of process models, as they supply a description of the process structure and complexity. Considering the importance of Business Processes models, the use of metrics may be the key to obtain high quality models that are useful as support to improve the processes maintenance, updating and adaptation. Based on metamodels of the BPDM standard, a proposal of metrics for Business Processes models is submitted; these metrics are specified in OCL and their application results are outlined in a study case.