We used the Pediatric Health Information System (PHIS) administrative database to compare the incidence of childhood tuberculosis at Children's National Medical Center (CNMC) in Washington, DC, with national rates and evaluated PHIS as an epidemiologic tool. The incidence rate of tuberculosis at CNMC was approximately twice that of the national PHIS rate (incidence rate ratio, 1.9; 95% confidence interval 1.4-2.5). Of the 51 cases listed by PHIS as tuberculosis at CNMC between 2003 and 2007, 41 represented active tuberculosis validated by internal chart review, with a positive predictive value of 80%.