As the medical informatics field evolves, new functions appear as the focus of interest; a more advanced management of terminology is one of them. Using comprehensive and detailed terminology to represent clinical rules in computer systems, associated with patient information, would allow clinical software to provide patient specific recommendations or alerts. In order to uniform data collection through our HIS, and lay the foundations for future clinical decision support systems, we decided to move from our previous classification-based medical record into new terminology services built around Snomed CT, Spanish Language Version. This paper describes the characteristics of our Terminology Server. The most important achievements of our new terminology system are the centralization of knowledge representation, using a much more detailed terminology system. Clinical data entered at any place of the institution and level of care, is represented uniformly through the whole health information system.