OBJECTIVE: To assess whether publication of national treatment guidelines improved the management of early RA in the UK. METHODS: Incident diagnoses of RA in persons aged over 18 years from 1995 to 2010 were identified from the Clinical Practice Research Datalink. Using a natural experimental study design, interrupted time series analysis was used to assess whether trends in the proportion of patients receiving DMARDs, within 3 and 12 months of diagnosis, changed following publication of British Society for Rheumatology guidelines in 2006. RESULTS: Between 1995 and 2010, 11 772 incident cases of RA were identified. There was a progressive increase in the proportion of patients prescribed any DMARD within 12 months from 43.3% in 1995 to 78.5% in 2010. After publication of the British Society for Rheumatology guidelines, the proportion of patients prescribed any DMARD within 12 months increased by 4.2% (P = 0.053). Prior to the guidance, prescribing was increasing by 1.64% per year, compared with 3.55% per year after publication (P < 0.001). CONCLUSION: Guidelines published by a national body can improve the proportion of patients receiving DMARD treatment in the first year after diagnosis of RA.