Attention Deficit Hyperactivity Disorder (ADHD) is a developmental disorder affecting up to 5% of children and adults and is underdiagnosed in many European countries. The process of access to care for this disorder is complex and variable across countries. In general, those affected, or their caregiver, will seek help through their primary care practitioners who are then often responsible for referral to other professionals for diagnosis and provision of treatment. Previous studies have highlighted that many barriers to recognition exist in primary care settings (such as misconceptions, lack of education or lack of resources), preventing access to care for this population and potentially affecting diagnosis rate. This systematic review aims to establish the barriers and facilitators with regard to attitudes, beliefs and experiences of ADHD within primary care. Electronic searches of multiple databases identified 3898 articles of which 48 met our inclusion criteria – primary care professionals from any country, understanding, knowledge, awareness, attitude and recognition of ADHD. Four main themes were identified, 1) need for education, 2) misconceptions and stigma, 3) constraints with recognition, management and treatment, 4) multidisciplinary approach. The findings suggest many interacting factors are at play in the recognition of ADHD by primary care practitioners with a strong recurring theme of a significant need for better education on ADHD. Implications for research and practice are discussed, suggesting that educational interventions for primary care practitioners could improve the recognition of ADHD in this setting