In England the Department of Health has funded specialist clinical services aimed at diagnosing and managing the symptoms of chronic fatigue syndrome (CFS). These services are not available to those who do not fulfil the diagnostic criteria for CFS. This service evaluation examined the proportion of those referred to a specialist CFS service fulfilling the Fukuda diagnostic criteria for CFS and the alternative fatigue-associated diagnoses. The CFS database was interrogated to include every patient referred to the Newcastle service from November 2008 to December 2009. All medical notes were reviewed and the diagnosis, sex and age recorded. Data were compared to a previous service evaluation (2005-07). In 2008-09, 260 subjects were referred: 19 referrals per month (260/14), compared with 17 referrals per month in 2005-07 (375/24). The proportion of patients diagnosed with CFS increased significantly compared with 2007 (36% [20/56] vs 60% [157/260]; p < 0.0001). Of the 40% of patients subsequently found not to have CFS the most common diagnosis was fatigue associated with a chronic disease (47% of all alternative diagnoses); 20% had primary sleep disorders, 15% psychological/psychiatric illnesses and 4% a cardiovascular disorder. Thirteen per cent remained unexplained (5.2% of the total referrals). This study found a significant increase in the proportion of patients referred to National Health Service (NHS) CFS services diagnosed with CFS. A large proportion of patients presenting with fatigue are not eligible for referral to the Department of Health specialist fatigue services, which represents an unmet need in terms of symptom management in current NHS services.