We aimed to quantify the rate of Mycobacterium tuberculosis disease (TB) among a cohort of patients with rheumatoid arthritis (RA) and to assess whether the independent use of disease-modifying antirheumatic drugs (DMARDs) is associated with the risk of developing TB.The study was performed using the PharMetrics Patient-Centric database (PharMetrics). The cohort consisted of all subjects with > or =1 occurrence of a diagnosis of RA during an inpatient or outpatient visit during the period of September 1998 through December 2003. Conditional logistic regression was used in a nested case-control analysis to estimate the rate ratio (RR) of TB with any use of biological or traditional DMARDs during the year before the index date. We also assessed the interaction between DMARDs and the current use of corticosteroids.The cohort consisted of 112,300 patients with RA. A total of 386 cases of TB were identified, which resulted in an overall rate of 2.19 cases per 1000 person-years. The adjusted RR of TB for biological DMARD use is 1.5 (95% CI, 1.1-1.9). Use of traditional DMARDs was also independently associated with TB (RR, 1.2; 95% CI, 1.0-1.5). RRs of developing TB disease with the use of biological or traditional DMARD were lower among current users of corticosteroids than among noncurrent users of corticosteroids.We found that the use of biological and traditional DMARDs is associated with an increased risk of developing TB in patients with RA, mainly among noncurrent users of corticosteroids.