Our preliminary (unpublished) results in a series of 90 patients, also from Brazil, in the state with the country’s highest tuberculosis incidence rate (Rio de Janeiro), indicate that PCR and ADA have sensitivities of 80% and 84.6%, respectively, which are much higher than those reported by Lima et al.1 Specificity was 84% and 96%, respectively. The only false-positive case of ADA was a patient with empyema, which has distinct clinical features and can thus be easily distinguished from pTB. The best accuracy was achieved using an ADA cutoff of 34.6 U/L, as determined by a receiver operating characteristic curve. When combined, PCR increased ADA sensitivity to 92.3% at the expense of specificity, which dropped to 80%. Therefore, in our hands, PCR appears to add cost to the diagnostic approach of pTB without offering a significant advantage over ADA alone. ADA activity detection in pleural fluid alone is a very useful tool for the diagnosis of pTB, and its combination with PCR is not presently warranted in low-income countries with a high prevalence of tuberculosis.