Objective To evaluate the effect of different concomitant disease modifying antirheumatic drugs (DMARDs) on the persistence with antitumour necrosis factor (anti-TNF) therapies in patients with rheumatoid arthritis (RA). Method This analysis included 10 396 patients with RA registered with the British Society for Rheumatology Biologics Register, a prospective observational cohort study, who were starting their first anti-TNF therapy and were receiving one of the following DMARD treatments at baseline: no DMARD (n=3339), methotrexate (MTX) (n=4418), leflunomide (LEF) (n=610), sulfasalazine (SSZ) (n=308), MTX+SSZ (n=902), MTX+ hydroxychloroquine (HCQ) (n=401) or MTX+SSZ+HCQ (n=418). Kaplan–Meier survival analysis was used to study the persistence with anti-TNF therapy in each DMARD subgroup up to 5 years. Multivariate Cox proportional hazard models, stratified by anti-TNF used and start year and adjusted for a number of potential confounders, were used to compare treatment persistence overall and according to the reason for discontinuation between each of the DMARD subgroups, using MTX as reference. Results One-year drug survival (95% CI) for the first anti-TNF therapy was 71% (71% to 72%) but this dropped to 42% (41% to 43%) at 5 years. Compared with MTX, patients receiving no DMARD, LEF or SSZ were more likely to discontinue their first anti-TNF therapy while patients receiving MTX in combination with other DMARDs showed better treatment persistence. Conclusions These results support the continued use of background DMARD combinations which include MTX. Consideration should be given to the discontinuation of LEF and SSZ monotherapy at the time anti-TNF therapies are started, with the possible exception of the SSZ+ETN combination.