Abstract Background Advance care planning (ACP) facilitates communication and understanding of preferences, nevertheless the use of ACPs in primary care is low. The uncertain course of dementia and the inability to communicate with the patient living with dementia are significant challenges for GPs to initiate discussions on goals of care. Methods A cross-sectional survey, using a purposive, cluster sample of GPs across Northern Ireland with registered dementia patients was used. GPs at selected practices received the survey instrument and up to four mail contacts was implemented. Results One hundred and thirty-three GPs (40.6%) participated in the survey, representing 60.9% of surveyed practices. While most respondents regarded dementia as a terminal disease (96.2%) only 37.6% felt that palliative care applied equally from the time of diagnosis to severe dementia. While most respondents thought that early discussions would facilitate decision-making during advanced dementia (61%), respondents were divided on whether ACP should be initiated at the time of diagnoses. While most respondents felt that GPs should take the initiative to introduce and encourage ACP, most survey participants acknowledged the need for improved knowledge to involve families in caring for patients with dementia at the end of life and that a standard format for ACP documentation was needed. Conclusion Optimal timing of ACP discussions should be determined by the readiness of the patient and family carer to face end of life. ACP discussions can be enhanced by educational strategies directed towards the patient and family carer that enable shared decision-making with their GP when considering options in future care.