Objectives To overcome the shortage of organ donors, Scotland and England are introducing an opt-out organ donor registration system in 2020. This means individuals will be automatically considered to consent for donation unless they actively opt-out of the register. Research has found that emotional barriers play a key role in donor decisions under opt-in legislation, yet little is known about factors that influence donor decisions under opt-out consent. Our objectives were to investigate attitudes towards organ donation and opt-out consent from individuals who plan to opt-out, and to explore the reasons why they plan to opt-out. Design Qualitative interview study. Methods Semi-structured interviews were conducted with 15 individuals from Scotland (n = 14) and England (n = 1) who self-reported the intention to opt-out of the register following the legislative change to opt-out. The interviews were transcribed verbatim and analysed using thematic analysis. Results Three main themes were identified: (1) consent versus coercion, which describes the perception of freedom of choice under an opt-in system and fears of 'government interference' and threatened autonomy under opt-out, (2) self-protection, encompassing fears of medical mistrust, bodily integrity concerns, and apprehension regarding the recipient selection process, and lastly, (3) 'riddled with pitfalls', which includes the notion that opt-out consent may increase susceptibility of stigma and reproach when registering an opt-out decision. Conclusions This study reinforces existing opt-in literature surrounding medical mistrust and bodily integrity concerns. A threat to one's autonomous choice and heightened reactance arising from perceptions of unwarranted government control have emerged as novel barriers. Statement of contribution What is already known about this subject? Although around 90% of individuals in the United Kingdom support organ donation, just 40% are actively registered as donors. As part of measures to improve rates of organ transplantation, Scotland and England are moving to an opt-out organ donation consent system in 2020. Existing research has shown that feelings and emotions are important factors that influence donor relevant decisions under the current opt-in system, but little research has explored potential deterrents under the new plans for opt-out consent. Minimizing the number of people opting out of the donor register is key to ensure sustained rates of transplantation. What does this study add? This study explored why people plan to opt-out of the new system in Scotland and England. Medical mistrust and bodily integrity concerns remain as salient barriers under opt-out laws. Fears of unwarranted government control and a perceived threat to one's freedom of choice emerged as a novel barrier.