Aim To determine the prevalence of retinal haemorrhages in infants with pertussis infection with the purpose of clarifying the differential diagnosis of the cases of abusive head trauma.

Methods Prospective study of children aged 15 days to 2 years admitted to our hospital with a diagnosis of pertussis over a period of 4 years (May 2004–May 2008). All children underwent one detailed ophthalmological examination within 72 h of admission. If retinal haemorrhages were detected, further investigation was undertaken to rule out systemic disorder or maltreatment.

Results 35 children with pertussis infection were examined. None was found to have retinal haemorrhages. Therefore, applying Wilson's method, the data suggest with 95% confidence that the true effect estimate for retinal haemorrhage occurring due to symptomatic pertussis infection requiring admission to hospital is no higher than 9.9%.

Conclusions Pertussis infections are unlikely to cause retinal haemorrhages in children under 2 years of age.