INTRODUCTION: Over the past few decades, Australia's population and multicultural landscape have changed significantly. The growing population of culturally and linguistically diverse (CALD) groups requires changes in the provision of health services to meet their special health needs. CALD populations face multiple challenges in accessing health services. Access to and utilisation of health services are multifaceted and are influenced by factors at individual, household and societal levels. Additionally, poor access to and utilisation of health services are affected by health systems, organisations and provider factors. Given the growing number and diversity of CALD populations in Australia, including in regional areas, a better understanding of these factors is crucial to identifying existing gaps and health service needs. This qualitative study aimed to explore factors affecting effective access to and utilisation of health services among CALD populations in the south and east regions of South Australia (SA). METHODS: The 'access to health service' theoretical framework developed by Levesque and colleagues guided this study. A qualitative study was conducted between December 2018 and April 2019 through: (a) individual interviews with service providers (n=23); and (b) focus group discussions (n=4) with CALD populations in three regional towns in SA. Data from interview and focus group discussions were analysed using inductive and deductive analysis approaches. RESULTS: Poor health literacy among CALD populations, such as difficulties in searching and understanding health information, and seeking the right services at the right time, were significant barriers to effective navigation and utilisation of health services. Factors leading to low health literacy included language and communication problems, the complexity of the Australian health system, and poor availability of multilingual health materials to health providers and community members. Interpreting services were widely used to facilitate communication between patients and health providers, although these were inadequate and needed some improvements. A shortage and high turnover of health providers as well as distance and transport difficulties were major barriers to the accessibility of health services. Poor access to female-specific services to meet cultural needs in some population groups and the lack of cultural competency training were key issues reported in relation to acceptability and cultural appropriateness of health services. Additionally, the cost of services and poor service affordability hampered access to and utilisation of some services. Finally, broader social determinants of health such as poor housing and unemployment were reported as factors negatively affecting access to health services by CALD populations. CONCLUSION: This study revealed key factors facilitating or constraining access to and utilisation of health services by CALD populations living in regional SA. A combination of strategies at different levels of health services is required to ensure services are accessible, culturally appropriate, acceptable and affordable. Improving accessibility is necessary in order to reduce inequity in health access and outcomes among the growing CALD populations in Australia.