BACKGROUND: Rare diseases (RDs) are life-threatening or chronically debilitating and offer a high level of complexity. The aim of this study is to assess medical students' knowledge and awareness of RDs as well as their perceptions of potential measures to boost training in RDs. The cross-sectional survey was conducted at the Medical University of Plovdiv, Bulgaria, in 2019. The questionnaire contained 12 questions, divided into three main categories: (1) sociodemographic profile; (2) knowledge and awareness of RDs; and (3) attitudes about potential measures to improve training in RDs. RESULTS: A total of 1189 medical students completed the survey with an overall response rate of 56.4%. Only 13% of participants knew the correct definition of RDs, and a low overall level of awareness was found with regard to orphan drugs (20.3%) and genetic counselling and testing (0.5%). Respondents believed that society as a whole was largely unaware of RDs as a major public health issue. Students suggested elective courses, and invited lectures by RDs experts, and participation in research projects as the most preferred measures to improve undergraduate training. CONCLUSIONS: It is crucial to address the gaps in medical students' knowledge and awareness of RDs. University curricula should consider incorporating different RDs training modalities. It is essential to encourage various stakeholders to play a more proactive role and to collaborate in these activities. Involvement of patient organisations and advocacy groups might enhance students' knowledge of the challenges faced by people with RDs. Not least, the media should be partners in this important endeavour as well.