This scoping review explores the unique challenges and needs faced by ageing individuals, aged 45 and above, in opioid agonist treatment (OAT), noting the earlier onset of age-related impairments among this population. The literature search was conducted in PsycINFO, EMBASE, MEDLINE, CINAHL, and Web of Science. A total of 28 observational studies were included. Five topics were identified: health, treatment, substance use, demographic, and social aspects. Findings reveal that, while health and age-related concerns are often discussed in the literature, limited attention has been given to gender differences, social factors such as financial issues, and psychological factors, which are also critical aspects of the lives of ageing individuals undergoing OAT. This review emphasizes the importance of expanding research to address these gaps, ultimately aiming to improve their overall well-being.