Anaesthetists recognize that children with Down's syndrome require special management in a number of clinical situations. There is a widespread clinical impression that it is difficult to achieve adequate sedation and that, following cardiac surgery, these children require higher doses of morphine and additional sedative agents compared to patients without Down's syndrome. We conducted a retrospective chart review of 16 Down's syndrome and 16 matched non-Down's syndrome children who underwent cardiac surgery between 1984 and 1991. The average dose of morphine (continuous infusion) administered per hour was higher in the Down's syndrome group than in the non-Down's syndrome group. The difference was not statistically or clinically significant until the third postoperative day. Down's syndrome patients were more likely to still be receiving morphine on Day 3 than non-Down's patients (P < 0.05). The Down's syndrome patients were also more likely to receive additional sedatives and skeletal muscle relaxants.