Many options are currently available for the laboratory diagnosis of tuberculosis. This chapter describes the utility and drawbacks of the different tools commonly employed for the diagnosis of tuberculosis. It includes a discussion on sputum microscopy: its role and its attendant advantages and disadvantages. It compares solid and liquid cultures in relation to their respective roles in diagnosis. It also outlines the differentiation of Mycobacterium tuberculosis from other species based on phenotypic tests and molecular methods, and explores the issues inherent in the interpretation of the different nuclear amplification tests and line-probe assays.