Purpose: The participation rate in the Danish National Screening Program for Colorectal Cancer is around 60%. Since early detection of cancer through the colorectal cancer screening program (CRCS) reduces mortality rates, it is important to understand why people do not participate. The aim of this study was therefore to examine in depth why some people do not participate in the Danish CRCS program. Methods: Individual semi-structured interviews were conducted with 18 people who had not participated in the national CRCS program. Data was analyzed using an inductive hermeneutic approach. Results: The analysis uncovered three main themes describing barriers to screening: (a) the accountability for ensuring personal health covered the following sub-themes: (i) when invitation is out of sight it is out of mind, (ii) aversion against own stool sample collection, and (iii) the perceived risk of getting colorectal cancer (CRC); (b) attitudes towards the healthcare system and its organization covered the following sub-themes: (i) positivity towards CRCS, (ii) trust in the healthcare system, (iii) lack of internal communication in the healthcare system, and (iv) wish for involvement of the general practitioner (GP); (c) knowledge about disease and screening covered the following sub-themes: (i) knowledge about CRC and CRCS, (ii) wish for information via new channels, and (iii) CRC is rarely something you talk about. Conclusion: Among the informants included in this study, lack of participation in the CRCS program was not due to an active opt-out, as most informants had intentions of participating. The informants thought it would motivate them to participate if their GP would remind them of the screening program.