In the pre-vaccine era, there was little information about clinical pertussis in adults, although deaths were noted. Today Bordetella pertussis infection in adults is noted to cause a full spectrum of clinical manifestations. If single serum serologic diagnosis becomes routine, the finding of adult cases would increase dramatically. Reported adult pertussis was rare in the pre-vaccine era and it has been increasing markedly in the present era. In the present vaccine era, data on adult pertussis and B. pertussis infection have been gathered by studying prolonged cough illnesses, serologic studies determining recent infections and prospective rate of illness studies. These studies suggest that approximately 15% of prolonged cough illnesses are due to B. pertussis infections; the yearly rate of infection is approximately 6% and the yearly rate of B. pertussis infection with clinical manifestations is >500/100,000. The duration of protection following natural infection or vaccination is relatively short. Therefore, unless new and better pertussis vaccines are developed, lifelong vaccine-induced immunity is not possible.