BACKGROUND: Evidence on the impact of tuberculosis (TB) treatment on lung function is scarce. The aim of this study was to evaluate post-treatment sequelae in drug-susceptible and drug-resistant-TB (DR-TB) cases in Mexico and Italy.METHODS: At the end of TB treatment the patients underwent complete clinical assessment, functional evaluation of respiratory mechanics, gas exchange and a 6-minute walking test. Treatment regimens (and definitions) recommended by the World Health Organization were used throughout.RESULTS: Of 61 patients, 65.6% had functional impairment, with obstruction in 24/61 patients (39.4%), and 78% with no bronchodilator response. These effects were more prevalent among DR-TB cases (forced expiratory volume in 1 s/forced vital capacity [FEV1/FVC] < lower limit of normality, 14/24 vs. 10/34; P = 0.075). DR-TB patients showed moderately severe (FEV1 < 60%) and severe obstruction (FEV1 < 50%) (P = 0.008). Pre- and post-bronchodilator FEV1 and FEV1/FVC (% of predicted) were significantly lower among DR-TB cases. Plethysmography abnormalities (restriction, hyperinflation and/or air trapping) were more frequent among DR-TB cases (P = 0.001), along with abnormal carbon monoxide diffusing capacity (DLCO) (P = 0.003).CONCLUSION: The majority of TB patients suffer the consequences of post-treatment sequelae (of differing levels), which compromise quality of life, exercise tolerance and long-term prognosis. It is therefore important that lung function is comprehensively evaluated post-treatment to identify patient needs for future medication and pulmonary rehabilitation.