Open data has been promoted as a tool to improve the transparency, robustness, and efficiency of scientific research. However, the perspectives of participant communities, particularly those who are marginalised, are often overlooked in discussions around open data. For the first time, this paper examines the views of autistic adults and parents of autistic people regarding open data practices in autism research. Thirty interviews were conducted, which considered participants’ views on different degrees of openness of research data, and the factors that would influence their level of comfort with their and/or their child’s data being shared. Pre-registered reflexive thematic analysis that interrogated power dynamics in the participants’ statements led to the development of two themes: (1) Narratives of Research, and (2) Vulnerability and Risk in Research Participation. These themes reflected how narratives and risks around open data were experienced both individually and collectively. Participants acknowledged the potential benefits of open data for knowledge generation and improving services, but also expressed concerns about misuse, re-identification, and interpretations from secondary researchers leading to harmful narratives. Most participants preferred restricted access models over fully open data. The findings highlight the importance of meaningful engagement with participant communities to ensure ethical and transparent open data practices. We hope this work will inform not only autism researchers but also others working with marginalised populations on decision making about open data.