Pertussis or whooping cough is typically characterised by paroxysms of coughing with a whooping sound during inhalation. It is thought to be under-diagnosed generally. Whooping cough is caused by Bordetella pertussis and is highly contagious. Although childhood immunisation has been effective in preventing the disease, outbreaks in Australia have been associated with waning immunity in older children and adolescents. The peak incidence of infection now occurs in people aged 15 or older. When given early in the illness, antibiotics can decrease the infectious period, but have no effect on the duration or severity of disease. Symptomatic treatment of cough has shown no clear benefit. Antibiotic prophylaxis of contacts is recommended for certain high-risk groups, but there is limited evidence of its effectiveness. Although infants remain the most at risk for severe, life-threatening disease, it is adolescent and adult booster immunisation which remains critical for prevention programs.