OBJECTIVES: Gout is one of the most common inflammatory arthritides; it is commonly managed in primary care in the UK and has been associated with poor cardiovascular (CV) outcomes. Allopurinol use has been associated with improved outcomes, particularly at a higher dose (>600mg/day); however, published studies have shown that prescribed doses in the UK are 300mg or less. Adherence to allopurinol has not been well evaluated in the UK; we estimate the impact of adherence to allopurinol on CV in gout patients in the UK. METHODS: The Health Improvement Network (THIN) database from 1990 to 2009 was examined; patients aged 18+ were identified using Read and drug codes. The CV-related outcomes were myocardial infarction (MI), heart failure, stroke, peripheral thrombosis, angina and coronary artery bypass. Adherence was measured using proportion of days covered (PDC). Descriptive statistics were calculated and Kaplan-Meir survival curves were constructed for different levels of adherence (PDC in quartiles). Analyses were performed in a subset of patients that experienced a particular CV event during the observation period.  RESULTS: A total of 91,665 gout patients were identified, 39,747 of which were prescribed allopurinol; of these, 9% had MI, 18% had heart failure, 15% had stroke, 4% had thrombosis, 16% had angina and 5% had coronary artery bypass. Mean PDC in patients prescribed with allopurinol was 0.72 (SD±0.28). Higher PDC was associated with increased survival time in all CV events except for angina. PDC > 0.75 resulted in substantially greater survival time. High adherence has the greatest impact in MI and coronary artery bypass.  CONCLUSIONS: Greater adherence to allopurinol appears to be associated with better CV outcome in all conditions except angina. A more profound effect in PDC higher than 0.75 suggests that high adherence is needed to achieve clinical benefit.