An outbreak of infection due to Staphylococcus aureus phage-type 52, resistant only to penicillin, occurred in children's wards primarily in a neonatal intensive care unit. The outbreak involved 86 infants; the majority presented with conjunctivitis, wound infections, boils, omphalitis and otitis externa. Seven per cent of these infants (six of 86) also had septicaemia. In addition, 6% (five of 86) were colonized by this phage type and the most common site of carriage was the umbilicus. The outbreak was contained by eradication of nasal carriage among the staff members and also by standard infection control measures.