Five patients developed overwhelming infection as a result of congenital asplenia, which was previously unsuspected in all cases. Each illness followed a fulminant course resulting in death within 24 hours. They illustrate the respective roles of Haemophilus influenzae infection (n = 4) and adrenal haemorrhage (n = 4) in this condition. We suggest a management protocol for screening infants with abnormalities of the atria or viscera with splenic ultrasound and examination of a blood film for Howell-Jolly bodies. Vaccination and prophylactic antibiotics should be considered for those at risk. Vigorous use of parenteral antibiotics and steroids in suspected infection is recommended.