BACKGROUND Adolescents and adults are the main reservoir of pertussis infection in Australia today. Diagnosis in these age groups can be difficult because of atypical clinical presentations and limitations of laboratory investigations. OBJECTIVE This article discusses the common presentation of pertussis in adults and adolescents, the use and limitations of laboratory testing, and appropriate treatment and prophylaxis. DISCUSSION The reason for treating cases and providing chemoprophylaxis for contacts is to prevent infection in infants, who account for 90% of deaths from pertussis. Treatment with the newer macrolides appears to be as effective as erythromycin and with less side effects; however, roxithromycin should not be used as its in vivo efficacy is unproven. The majority of pertussis cases will be seen in general practice - most likely during the infectious period - therefore general practitioners need to consider being vaccinated with dTpa against pertussis.