OBJECTIVES: The quality of life (QoL) of informal caregivers can be adversely affected by a number of factors. This issue, however, has not been well explored for carers of people with Parkinson’s disease (PD). This study aims to determine the main influences on carer QoL in this population. METHODS: Carers completed the PDQ-Carer, a 29 item instrument incorporating four dimensions (Social and Personal Activities, Anxiety and Depression, Self-Care and Stress). PWP completed the PDQ-39, a 39 item instrument containing eight dimensions (Mobility, Activities of Daily Living, Emotional Well-Being, Stigma, Social Support, Cognitions, Communication and Bodily Discomfort). Regression analyses were performed to identify factors related to carer QoL. RESULTS: The sample comprised 238 carers (mean age 68.20 years) and 238 PWP (mean age 71.64). The mean duration of caring was 8.13 years. Carer Social and Personal Activities were significantly related to caregiver age (p <0.01), PWP Mobility (p <0.01) and Cognitions (p <0.01). Carer Anxiety and Depression were significantly related to caregiver age (p <0.01), length of caregiving (p <0.05), PWP Emotional Well-Being (p <0.05), Cognitions (p <0.01) and Communication (p <0.05). Caregiver Self-Care was significantly related to caregiver age (p <0.05), length of caregiving (p <0.05), PWP Mobility (p <0.01), Emotional well-being (p <0.05) and Cognitions (p <0.05). Caregiver Stress was significantly related to caregiver age (p <0.05), length of caregiving (p <0.01) and PWP Cognitions (p <0.01). CONCLUSIONS: Results suggest multiple influences on caregiver QoL. Carer age and length of time in the caregiving role appear to be of particular importance, as do PWP levels of mobility and cognitive impairment. Practitioners and service providers should be aware of the heightened impact of PD on carers over time and also as PWP symptoms deteriorate.