New data are emerging on the use of palivizumab as prophylaxis against infection with the respiratory syncytial virus in infants with congenital cardiac disease. Following a 4-year multicentre randomised trial, it was shown that prophylactic injections with palivizumab were effective and safe for such children. Prophylaxis consists of 5, monthly, intramuscular injections of palivizumab, at a dose of 15 mg/kg, given during the season for infection with the respiratory syncytial virus. Timing is at the discretion of the physician, depending on the onset of the season locally. It is suggested that, in the United Kingdom, this should be commenced in mid-September. To help clinicians to identify appropriate candidates for palivizumab, a working group of the British Paediatric Cardiac Association has developed recommendations. Infants, namely those under 1 year old, with congenital cardiac disease likely to benefit from prophylaxis include those with haemodynamically significant lesions, particularly increased pulmonary blood flow with or without cyanosis; pulmonary venous congestion, pulmonary hypertension or long-term pulmonary complications, residual haemodynamic abnormalities following medical or surgical intervention (patients who have undergone cardiopulmonary bypass should receive an injection as soon as they are medically stable), cardiomyopathy requiring treatment, and congenital cardiac disease likely to need hospital admission for medical or surgical intervention during the season of infection with the virus. Prophylaxis with palivizumab may also be indicated, at the discretion of the physician, in some children with complex cardiac disease over the age of 1 year. Children less likely to benefit from prophylaxis are those with haemodynamically insignificant disease, or those with lesions adequately corrected by medical or surgical intervention.