Evaluating the complexity of business processes during the early stages of their development, primarily during the process modelling phase, provides organizations and stakeholder with process models which are easy to understand and easy to maintain. This presents advantages when carrying out evolution tasks in the process models - key activities, given the current competitive market. In this work, we present the use and validation of the CFC metric to evaluate the complexity of business process models developed with BPMN. The complexity is evaluated from a control-flow perspective. An empirical evaluation has been carried out, in order to demonstrate that the CFC metric can be useful when applied to BPMN models, providing information about their ease of maintenance. Keywords. Business process models, BPMN, Measurement, Validation.