The sensitivity of microscopy for the diagnosis of tuberculosis (TB) is around 50% but decreases by about 15% in patients with suspected TB who are coinfected with HIV. Here, we compared the accuracies of three microscopy methods for processing sputum smears (concentration by centrifugation with or without N-acetyl-L-cysteine [NALC] and concentration by filtration on a polycarbonate membrane) to that of culture on Ogawa-Kudoh medium as the gold standard method. Sputum samples were obtained from 432 patients with suspected pulmonary TB, of whom 60% were infected with HIV. Analysis was performed using the first specimen. Compared to the gold standard culture, the small-membrane-filter (SMF) method was the most sensitive microscopic method. In HIV-infected TB patients, the sensitivity of the SMF method was significantly higher than those for centrifugation of sputum samples with or without NALC treatment (61.9%, 47.6%, and 45.2%, respectively; P ‫؍‬ 0.001). Similarly, in TB patients without HIV infection, the sensitivity of the SMF method was significantly higher than those for centrifugation of sputum samples with or without NALC treatment (81.8%, 63.6%, and 57.5%, respectively; P ‫؍‬ 0.001). In the two study groups, TB patients with or without HIV, no significant differences between the specificities of the three methods were observed. Handling of the second sputum sample similarly by centrifugation with or without NALC and by the SMF method increased positivities by 13%, 11%, and 4%, respectively. The overall agreement between microscopy and culture was above 90% for all groups. Microscopic evaluation of the sputum samples treated with NALC compared to those not treated with NALC did not show any increase in sensitivity. Altogether, the sensitivity of the SMF method is higher than those of the other two microscopic methods studied without a loss of specificity. Diagnosing tuberculosis (TB) in HIV-infected patients still presents a major challenge since clinical and radiological findings are often atypical (1, 2), and many cases of smear-negative pulmonary TB are undiagnosed (3). Sputum smear microscopy, a low-cost method, is important in resource-limited scenarios, where cultures are not available, but it provides a lower sensitivity in HIV-infected patients with suspected TB (4-6).Filtration on a polycarbonate membrane, the small-membrane-filter (SMF) method, was proved to have greater sensitivity and specificity than direct microscopy, even after centrifugation of sputum samples (7,8), but the HIV status of the populations was not reported in those studies.Under the routine conditions of a bacteriology laboratory, we evaluated this method in patients with suspected TB, most of whom were infected with HIV, along with bacilloscopy after centrifugation with or without decontamination. The three methods were compared to culture on solid medium (Ogawa-Kudoh [OK]), considered the gold standard for TB diagnosis in our setting, and their sensitivities, specificities, and Cohen's kappa coefficients were calculated. MAT...