Tuberculosis over the ages, has killed more people than any other infection has. Notwithstanding the advances in modern science, clinical diagnosis sometimes remains elusive, owing principally to the frequent paucibacillary occurrence of the disease and the slow doubling time of the organism; empiric treatment is often fraught with risks in the era of increasing drug resistance.This chapter attempts to provide an overview of the disease, beginning with the pathogenesis and its protean clinical presentations. It also discusses the recent evolution of molecular methods that have lately provided an impetus to early diagnosis with a clear opportunity to unmask drug resistance before initiating "blind", potentially ineffective, and sometimes harmful treatment with standard therapy.The chapter also provides insight into tuberculosis in special situations, and discusses briefly the treatments in uncomplicated cases as well as in special situations, and in instances of drug resistance. Preventive methods including current and upcoming vaccines are mentioned.Finally, a short discussion of the sequelae of tuberculosis-which have the potential to be confused with active disease-is presented.