Easy Language is a language variety that aims to make information more comprehensible and, ultimately, more accessible. Content in this variety is written and designed following a set of recommendations that have been published in different guidelines. However, it remains uncertain to what extent these recommendations are backed up by empirical research. The aim of this study is to review the existing literature that evaluates current recommendations in Easy Language guidelines, on the basis of the following research questions: (a) is there empirical research that evaluates current international Easy Language recommendations? and, (b) if so, what current international Easy Language recommendations are supported by empirical research and what results were obtained? To this end, we conducted a systematic literature review based on journal articles in three languages: Catalan, English, and Spanish. First, a systematic search was designed and performed in 10 databases of different fields of science. Then, we reviewed every article that resulted from the search and found that 6 publications out of the initial 617 met the inclusion criteria and could be considered relevant for the study. Based on the data extracted from the included publications, and after an overall review of our systematic search results, we safely state that there is indeed empirical research on some current Easy Language recommendations. Nevertheless, empirical research in the field (at least in the publication format and languages considered in our study) is not enough in terms of the number of publications, and the findings obtained are far from generalisable. Our literature review suggests future lines of research, and we hope that it fosters empirical studies in the field that help support the existing findings.