Perceived usability is an important requirement of educational software, affecting greatly student’s learning effectiveness and overall learning experience. Although the System Usability Scale (SUS) questionnaire is considered as a de facto standard for perceived usability evaluation, surprisingly, few studies are reporting results from evaluations related to Learning Management Systems. In addition, given that the questionnaire comprises 10 questions presented in English, its applicability in studies involving speakers of other languages is questionable. In this paper, a first step towards standardization of a Greek version of SUS in the context of Learning Management Systems perceived usability evaluation is reported. To this end, three studies involving 280 university students in both blended and distance learning education were conducted. Analysis of the results demonstrated the validity and reliability of the Greek version of SUS.