Variceal sclerotherapy has been performed in the pediatric population, but techniques and dosages of sclerosant recommended in the literature are largely empirical. Having accumulated much data through experience with sclerotherapy in children, we have identified patient and procedure variables associated with early and late complications. We reviewed our experience with 37 pediatric patients, ages 1-18, who underwent 150 sclerotherapy sessions. Sclerotherapy was associated with 12 early complications in 11 patients. Early complications were bleeding (five), respiratory problems (three), false channel formation (two), and gross hematuria (two). Four patients developed strictures. We identified the following variables associated with complications: for bleeding, platelet count less than 100,000/mm3; for respiratory complications and false channel formation, weight less than 12 kg; for false channel formation, dosage of sclerosant/kg/session greater than 1.75 ml/kg; for gross hematuria, total sclerosant/session greater than 20 ml. A need for more than six sclerotherapy sessions for obliteration of varices was associated with a greater frequency of stricture formation. Sclerotherapy can be performed safely in children. Patients less than 12 kg or with platelet counts less than 100,000/mm3 should be monitored carefully for respiratory complications and postprocedure bleeding. Sclerosant dosages greater than 1.75 ml/kg, or 20 ml total sclerosant, should be given with caution.