Autistic people experience more health conditions and earlier mortality. This study investigated views about a primary care health check for autistic adults to inform its design. Fifty-one people participated in consultation groups and interviews, comprising autistic adults (some with co-occurring intellectual disabilities), adults with intellectual disabilities, supporters and health professionals. Participants wanted the health check to cover physical and mental health and social functioning. They emphasised the importance of sharing information about individual needs and associated adjustments before the health check. They highlighted the need to change the way healthcare services communicate with autistic people, such as reducing phone contact and booking appointments online. They wanted individual choice in how the health check was completed, with video call or email offered alongside face-to-face. Participants raised the need for further training of primary care staff on autism, to highlight the diversity of experiences of autistic people and ways in which difficulties, such as pain, may present differently. Clinicians raised questions about the capacity of mental health and social care services to meet the additional needs potentially identified through the health check. This study represents a key step in the development and co-design of a UK primary care health check for autistic people. Lay abstract Autistic people are on average more likely to experience poor health than people who are not autistic. Health checks have been shown to improve access to effective healthcare. This study investigated people’s views about a primary care health check for autistic adults. We held discussion groups and interviewed autistic adults, adults with intellectual disabilities, supporters and health professionals. People wanted the health check to look at a person’s physical and mental health, and how they were doing socially. They thought people should be able to share information about their needs and the reasonable adjustments they would like before the health check. They wanted healthcare services to change the way they communicate with autistic people, such as being able to book appointments online rather than by telephone. They wanted a choice in how the health check was completed, with video call or email offered as well as face-to-face appointments. People thought further training of primary care staff on autism was needed, to increase awareness of the diversity of experiences of autistic people and ways in which difficulties, such as pain, may present differently to non-autistic people. Clinicians raised questions about whether mental health and social care services could meet the additional needs that might be identified through the health check. We used this information to design an NHS primary care health check for autistic people in collaboration with autistic people, supporters and health professionals.