AbstractSevere B. pertussis infection in infants is characterized by severe respiratory failure, pulmonary hypertension, leukocytosis, and death. This retrospective case analysis highlights the course and outcome of severe B. pertussis infection treated with extracorporeal membrane oxygenation (ECMO) at a single center. Over the last decade, out of a total caseload of nearly 800 infants and children, 12 infants with severe B. pertussis have been referred for ECMO therapy to our center. All infants with pertussis infection who received ECMO therapy were less than 3 months of age at presentation and unvaccinated. There was a high mortality rate (7 of 12 infants died), which was associated with an elevated neutrophil count at presentation and multiorgan dysfunction characterized by intractable pulmonary hypertension, persistent systemic hypotension, renal insufficiency, and fits. ECMO should be offered to children with pertussis infection and respiratory failure refractory to mechanical ventilation. However, further research is required to determine the optimal management for infants receiving ECMO therapy with this disease. Pediatr Pulmonol. 2003; 36:310–315. © 2003 Wiley‐Liss, Inc.