Tuberculosis (TB) is a leading cause of morbidity and death worldwide, with approximately two billion people infected and approximately two million annual deaths attributable to it. In 2011, there were an estimated 8.7 million new cases of TB and 1.4 million people died from TB. The microbiological diagnosis of pulmonary tuberculosis (PTB) plays a key role in routine and TB Control Programmes in developing countries. Concentration of acid-fast bacilli (AFB) in clinical specimens is an important step in the laboratory diagnosis of mycobacterial diseases. Bleach digestion of sputum prior to smear preparation has been reported to increase the yield of microscopy for diagnosing PTB. In the present study sputum smear microscopy by sedimentation followed by treatment with 4% sodium hypochlorite (NaOCl) solution for concentration of the AFB was evaluated. The use of NaOCl in the concentration of AFB in sputum is recommended for use in routine laboratory diagnosis of PTB in developing countries.