Barriers to healthcare experienced by Australian autistic adults have not been previously explored. We conducted a cross-sectional investigation of barriers to healthcare and associated factors from a subtle realism perspective. Perceived barriers to healthcare were obtained from the Barriers to Healthcare Checklist Short-Form (BHC). A total of 263 autistic and 70 non-autistic individuals completed the BHC. On average, autistic adults reported more barriers to healthcare (4.58) than non-autistic adults (0.76). Gender diversity, higher levels of generalised anxiety, greater global disability and less satisfaction with social support contributed to the experience of barriers to healthcare in autistic participants in regression modelling. Australian autistic adults face substantial barriers to healthcare. Understanding these barriers provides an opportunity to develop approaches to improve access; such as co-designing a healthcare access roadmap for autistic adults, with co-designed policies and practices which advocate for the needs of autistic adults.