BACKGROUND: Ambulance services are commonly used by older adults. The scope of services continues to adapt in response to more non-life-threatening calls, often due to the acute consequences of chronic illness. Frailty increases with increasing age, but it is not known how common or severe it is within patients conveyed to hospital by ambulance. METHODS: Open cohort of people aged ≥50 living in Wales between 2010 and 2017. Routinely collected electronic data on ambulance attendances resulting in conveyance were linked to primary care data within the Secure Anonymised Information Linkage databank, and the electronic Frailty Index was calculated. The prevalence and severity of frailty according to patient and incident characteristics was described. RESULTS: Of 1 264 094 individuals within the cohort, 23.8% were taken to hospital between 2010 and 2017, of which frailty was present in 84.3% of patients. There was an upward trend in the number of conveyances for patients with moderate and severe frailty across the years in all age groups. The distribution of frailty was similar across call categories, deprivation quintiles and out-of-hours incidents. Patients conveyed from residential homes had a higher level of frailty and comprised 8.7% of the total conveyances. CONCLUSIONS: The high prevalence of frailty within adults aged ≥50 with emergency conveyances suggests upskilling ambulance crews with frailty training to enhance their assessment and decision making may improve patient outcomes. The high proportion of conveyances from residential homes indicates scope for increasing integration of community services to provide more patient-centred care pathways.