The paper presents the enrichment of an existing e-referral / e-prescription application within a Regional Healthcare Information Network with security functionality, solving current authentication, integrity, non-repudiation and confidentiality issues and thus significantly enhancing the overall system security, operability, applicability and user acceptance. The application makes use of an underlying PKI framework, in order to provide strong authentication, digital signature, encryption and time-stamping services. XML is used for the representation of the healthcare data itself, the encrypted form of this data, as well as the relevant data security information, following W3C standards.