Interoperability is a requirement for the successful deployment of Electronic Health Records (EHR). EHR improves the quality of healthcare by enabling access to all relevant information at the diagnostic decision moment, regardless of location. It is a system that results from the cooperation of several heterogeneous distributed subsystems that need to successfully exchange information relative to a specific healthcare process. This paper analyzes interoperability impediments in healthcare by first defining them and providing concrete healthcare examples, followed by discussion of how specifications can be defined and how verification can be conducted to eliminate those impediments and ensure interoperability in healthcare. This paper also analyzes how Integrating the Healthcare Enterprise (IHE) has been successful in enabling interoperability, and identifies some neglected aspects that need attention.