Constipation is a common complication in critically ill children and it is occasionally resistant to the drugs typically used in treatment. Neostigmine has been used in some cases of refractory constipation in critically ill adults. There is no reference to its use in critically ill children. We describe 3 cases of refractory constipation in critically ill children treated with intravenous neostigmine by continuous infusion. Two patients responded well. There were no adverse effects. We conclude that continuous intravenous neostigmine can be effective in critically ill children with refractory constipation. Further studies are necessary to determine the dose and safety of the treatment.