To assess the impact of the sputum samples treatment by sodium hypochloride (NaOCl) 5% on the acid-fast bacilli (AFB) gradations in the tuberculosis diagnosis, 516 sputum samples were collected in 244 patients. The sputum smears made before and after expectorations treatment with NaOCl 5%, were stained by Ziehl-Neelsen hot method. The values obtained from the two microscopic readings were compared by using the chi2 test of McNemar. The statistical significance was set at p < 0.05. The results obtained before using NaOCl 5% showed that 357 samples were negative, while 41 were AFB scanty (gradation 1-9), 28, 40 and 50 were positive 1+, 2+ and 3+. After treatment, among 357 AFB negative expectorations, 14 (3.9%) were AFB-positive, while the AFB gradation increased for 77 (48.4%) in the 159 positive specimens. The two microscopic readings differ significantly (p = 0.001). The application of the process on a routine basis in the laboratory will require a reorganization of the tasks in order to give back the results to the patients in time. It is necessary to take into account the aspect of the samples.