This paper is a complete description and comparison of some of the most cited eHealth interoperability standards in the literature, openEHR, HL7 FHIR and CDISC. We searched the Scopus database using the keywords interoperability, information systems, and health. It was found that standards are needed to develop interoperability platforms for eHealth. We carried out additional research on the most cited standards, allowing us to analyze the characteristics and particularities of each one and make comparisons. As a result of this work, we defined a list of comparison criteria and evaluated the differences between these standards based on these criteria. The standards compared have some common characteristics, but they also have unique features for each of them, so the selection of the standard to use will depend on the characteristics and requirements of the eHealth platform you want to develop.