Objectives: The objectives of this study were the following: (i) assess interest levels in cardiothoracic surgery (CTS) among UK-based medical students, (ii) identify potential motivators and barriers to pursuing CTS training, (iii) explore the influence of gender on interest in CTS in greater depth. Methods: Medical students from all year groups across UK medical schools were invited to participate in a cross-sectional, national online survey. Responses were collected from 02/12/2019 to 08/12/2019. Results: 1675 medical students from 31 UK medical schools responded, with an estimated 5.3% response rate. Of the respondents, 33.7% respondents reported having exposure to CTS, primarily through their medical school or through extracurricular activities (48.4% and 38.8%, respectively). When assessing interest in CTS, 31.4% were interested in undertaking a career in CTS, with a larger proportion of students expressing interest with no exposure to CTS than those with exposure. However, interest in pursuing CTS decreased with exposure as medical students transitioned from pre-clinical to clinical stages. Additionally, male participants were more interested in seeking a CTS post than their female counterparts (38% vs. 27.6%). The length of training (p = 0.0009) and competitive nature (p < 0.0001) of gaining a CTS post were the primary deterring factor for female participants, compared to their male counterparts. Conclusions: This study shows the importance of quality of exposure and its impact on students' interests in pursuing a career in CTS. The negative relationship between exposure and interest in CTS can be associated with the realisation of the challenges that come with pursuing CTS. [ABSTRACT FROM AUTHOR]