Interoperability is one of the biggest issues in health informatics despite of the huge effort invested to solve it. Clinical Data Interchange Standards Consortium (CDISC) and Health Level 7 (HL7) are two of the most recognized institutions working on this field. Several systems are becoming compliant with their standards; however, the process to accomplish it is not always straightforward. In this manuscript, we present the successful implementation of the CDISC ODM and HL7 import and export functions for "MoPat", a web-based multi-language electronic patient-reported outcomes system. The system has been evaluated and tested and is currently being used for clinical study and routine data collection, including more than 10.000 patient encounters.