INTRODUCTION: Limited research exists that has examined the barriers that older adults (those aged 65 years and older) can encounter when given a Green Prescription (GRx). This study aimed to identify what general practitioners (GPs) perceived their older-aged patients' barriers were with regard to carry-ing out a GRx. This study also identified the strategies that GPs used to assist their older-aged patients in overcoming barriers to physical activity engagement. METHODS: Fifteen GPs from the Auckland region of New Zealand were interviewed individually. An inductive thematic approach was used to analyse data. FINDINGS: GPs identified chronic health conditions, fear of injury, transportation constraints, set routines and lack of confidence as being barriers that some of their older-aged patients have encountered when considering whether to become more physically active and, also, when engaging in actual physical activity. CONCLUSION: Physical activity interventions, such as the GRx programme, can have an important role in helping confer health-related gain for low-active older adults. To ensure that such interventions are successful on a long-term basis, practitioners need to be aware of the barriers that their older-aged patients can encounter when given a prescription for physical activity.