Background In 2015, approximately 2.16% of adults were recorded as having intellectual disabilities. UK government policy is that adults with intellectual disabilities should access mainstream health services. However, people with intellectual disabilities experience challenges when accessing primary and community health services that can lead to inequalities and shorter life expectancy. Objectives To map and review the evidence on access to primary and community health-care services for adults with intellectual disabilities and their carers. To identify influencing factors for gaining access to primary and community health-care services. To determine which actions, interventions or models of service provision improve entry access to these services for people with intellectual disabilities and their carers. Finally, to identify the gaps in evidence and provide implications for health care and recommendations for research. Data sources MEDLINE, The Cochrane Library, Web of Science, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Applied Social Sciences Index and Abstracts (ASSIA) and Education Resources Information Center (ERIC) were searched from 2002 to 2018. Review methods The mapping review methodology included an extensive literature search, article selection and data extraction of relevant abstracts. Findings from the mapping review informed the scope of the targeted systematic review. Methodology for the targeted systematic review included an extensive literature search informed by the mapping review, article selection, data extraction, quality appraisal and narrative synthesis. Results The mapping review included 413 studies with data extraction completed on abstracts. The targeted systematic review synthesised the evidence from 80 studies reported in 82 publications. During the review process, the team identified three key points at which people with intellectual disabilities potentially interacted with primary and community health-care services: identifying needs, accessing services and interaction during a consultation. In addition, there were a number of papers about interventions or innovations to improve access. Evidence from the studies was synthesised within the four clusters. Influencing factors were identified: staff knowledge/skills, joint working with learning disability services, service delivery model, uptake, appointment making, carer/support role, relationship with staff, time, accessible information and communication. The influencing factors were cross-cutting through the literature, with certain factors having more importance in certain clusters. Limitations The main limitation was the weak evidence base. The studies generally had small samples, had study designs that were open to potential biases and measured only short-term outcomes. Conclusions Health checks were found to help identify health needs and improve the care of long-term conditions. Important factors for accessing health services for adults with intellectual disabilities were consistency of care and support, staff training, communication skills and time to communicate, and provision of accessible information. Health professionals need to ensure that there is joint working between different services, clear communication and accurate record-keeping. Future research questions centre on the need to develop and value creative study designs capable of addressing the complex issues identified in the findings of the review for this complex population. Funding This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 5. See the NIHR Journals Library website for further project information.