The purpose of this study was to develop a valid and reliable psychometric scale to measure the perceived autonomy of postgraduate students in the Hellenic Open University and similar distance education environments. Two dimensions of autonomy, namely personal and educational, were revealed from the literature review and the preliminary study. For the evaluation of each dimension, two subscales were developed. Following two pilot studies, the initial item pool led to the development of a 25-items questionnaire, which was then administered to a sample of 239 postgraduate students. The exploratory factor analysis revealed two factors for the personal autonomy subscale, with 7 items in total, and two factors for the educational autonomy subscale, with 9 items in total. The Cronbach's alpha coefficient ranged between 0.623 and 0.717. A statistically significant gender difference was found only for the personal autonomy subscale and, more specifically, for the factor 'managing difficulties', where female respondents received a lower score than males.