The increasing use of digital services and technologies in health care calls for effective tools to evaluate the users’ eHealth literacy in order to better understand the users’ interaction with health technologies. We here present a systematic review of existing tools to measure eHealth literacy and for what these tools have been used to investigate. We identified eight tools, of which three of them are bases upon a conceptual model of eHealth literacy and the remaining five are dual tools, i.a. comprised of individual measures for health literacy and digital literacy. Of these eight tools, only one tool (The eHealth literacy Scale - eHEALS) was used in other studies than the one it was originally published in. eHEALS has primarily been used to establish eHealth literacy levels in different populations. Five of the studies have been conducted by examining eHealth literacy’s impact on health outcomes, and one study has established an association between high eHealth literacy levels and increased likelihood of attending colorectal cancer screenings in a Japanese population. The two other concept-based tools, eHLS and PRE-HIT, reflect an elaborated understanding of eHealth literacy. The five dual tools were primarily used to screen for adequate and inadequate health literacy and digital literacy. In conclusion, there is very little knowledge about individuals’ eHealth literacy and how it relates to health outcomes or the clinical course of specific diseases. New tools developed for the new age of social media and new technologies should be used as eHEALS may have some limitations.