Pertussis or whooping cough is an acute infection of the respiratory tract caused by the Gram-negative bacterium, Bordetella pertussis. The disease remains a major public health problem worldwide and affects persons of all ages; however, it is most severe in the infant population less than 4 months of age. This chapter reviews the definition, epidemiology, stages, symptoms, and complications of pertussis disease, describes the most accurate method to test for infection, lists the differential diagnosis for pertussis-like illness, and reviews the most effective antibiotics for its treatment and prevention. An overview of available pertussis-containing vaccines and the current recommendations for their use in different age groups are also presented.