Of 17,836 children admitted in 1959, 6.5% developed infection following admission; most of these seemed to be hospital-acquired. Respiratory infections were commonest (2.7%), then gastroenteritis (1.3%), staphylococcal infections including miscellaneous and postoperative wounds (1.1%), pyrexias (0.5%), miscellaneous and post-operative wound infections due to other bacteria (0.4%), "communicable" diseases (0.3%) and monilial infections (0.2%). Incidences were highest in infants and on certain wards incapable of segregating all infected cases. Only 14.3% of infections were severe. They contributed to 16 deaths but not as the sole cause. Hospital infections made over 2070 extra patient-days necessary. Wound infection followed 3.1% of 5052 surgical operations-2.1% when considering only clean sites. Seventy per cent were staphylococcal; antibiograms suggested that some were not of hospital origin. Staphylococcal disease, present on admission or hospital-acquired, occurred in 2.6% of patients. None of these incidences seemed unduly high. Many varied factors underlie hospital infections, and complete control is unlikely with present knowledge and facilities.