This is the first needs assessment of general practitioners (GPs) in relation to early detection of cancer in the Republic of Ireland. Data was collected using focus groups with 47 GPs and a national survey of 929 GPs. Overall,74.6% of survey respondents had >10 years experience in general practice and 22.7% were single handed. Distance from the practice to the nearest hospital to which they could refer patients for assessment of suspected cancer was <5 miles for 53.3% of GPs. The principle barriers identified were not confined to early diagnosis but apply to the diagnosis of cancer at any stage. These included delayed patient presentation, lack of direct GP access to investigations, difficulty with hospital referral, lack of clear recommendations for screening, poor communication with hospital services, inequitable access to hospital services and a need for further education and clinical practice guidelines. The barriers identified have serious implications for early detection of cancer in primary care and are remedial.