The infantile kidney is most vulnerable to damage from vesicoureteric reflux combined with urinary tract infection. A UTI, as well as giving rise to significant morbidity, may provide the clue to an underlying congenital abnormality such as obstructive uropathy. Urinary tract infection is less prevalent in circumcised boys and infants who are breastfed. Often the diagnosis of UTI is not thought of because of the non-specific nature of the symptoms in this age group and the difficulties of obtaining and interpreting urine cultures. Too little use and attention is paid to proper collecting bags and clean catch specimens. Suprapubic aspiration should always be considered in the septicaemic infant where UTI is high on the list of differential diagnoses. Escherichia coli is responsible for most UTIs although in very young infants, kidneys may be involved secondary to septicaemic infection. Antibiotic therapy should be prompt and investigations comprehensive in young infants. Most children with vesicoureteric reflux are managed conservatively with long term prophylactic antibiotics.