Despite advocacy and demand for psychiatric advance directives (PADs), uptake and implementation in clinical practice is low. We examine why PAD implementation has been difficult globally by reviewing barriers in existing evidence. The review includes 30 studies, and identified 13 barriers, clustered into system level barriers, health professional level barriers, and service user level barriers. The considerable barriers to uptake and implementation hamper PAD use. We propose several potential strategies for overcoming some of the barriers. In order to realise these strategies, additional research is needed, particularly more field-based and operational research to understand processes and difficulties experienced in clinical practice.