Between 1996 and 2005 the Serious Hazards of Transfusion (SHOT) scheme analysed 3239 reports of adverse reactions and events associated with transfusion of labile blood components in the UK. 321 reports (10%) related to transfusion of children under 18 years and 147/3239 (4·5%) to infants less than 12 months of age. There were 264 cases in children of ‘incorrect blood component transfused’, resulting from errors at all stages in the transfusion chain; 26/264 suffered actual or potential morbidity. Thirty acute transfusion reactions, three delayed transfusion reactions, 20 cases (three fatal) of transfusion-related acute lung injury, two cases (both fatal) of transfusion-associated graft-versus-host disease and two transfusion transmitted infections were reported. A population-based epidemiological study of transfused patients in 2004 showed that 4·2% of red cells are transfused to patients less than 18 years and 1·7% to infants less than 12 months. Interpretation of SHOT data against this context enabled the estimation of the incidence of an adverse outcome to be 18:100 000 red cells issued for children less than 18 years and 37:100 000 for infants less than 12 months, compared to 13:100 000 for adults. Adherence to relevant guidelines, knowledge of specialist transfusion needs of children and good communication are essential if this risk is to be reduced.