HL7v3 standard was designed to facilitate communication between all types of eHealth applications, regardless of the domain of activity. The exibility of the HL7v3 messages led, however, to proprietary denitions of HL7v3 messages and structures. In order to unify the communication in dierent domains, proles have been developed and standardized. In this context, testing plays an important role in assuring interoperability, as well. This paper presents a method to test the interoperability of HL7v3 applications, using the standardized TTCN-3 test scripting language and its corresponding TTCN-3 test system. The full testing process is described, highlighting all the components involved and providing guidelines for implementing them. This approach requires testers to be familiar to the TTCN-3 environment.