Failure to detect persons with TB can lead to continued spread of infection in the community. The WHO strategy for tuberculosis control (DOTS) relies on a network of laboratories that provide acid-fast bacilli (AFB) sputum smear microscopy. The AFB result determines the treatment and outcome of an individual TB patient. This document provides guidelines for a system of external quality assurance (EQA) and quality improvement for the testing laboratories that meets international standards. The guidelines presented are for provincial level laboratories (PRL), which provide training and supervision support to the district laboratory supervisors.