Twenty-four children, teenagers, and young adults (8 to 26 years old) with insulin-dependent diabetes mellitus were treated with continuous subcutaneous insulin infusion (CSII). Criteria for using CSII included persistent high glycohemoglobin (GHb) values and/or wide swings in blood glucose values despite arduous efforts to improve glycemia. Thirty percent discontinued CSII. Improvement was significant by three months for GHb and blood glucose values, but plateaued thereafter. Only three patients attained a normal GHb value. No predictors for degree of control were identified. Diabetic ketoacidosis did not occur more frequently with CSII. Electromechanical problems with the devices, patient errors, or local skin problems occurred in 50% of patients, although none produced ketoacidosis or severe hypoglycemia. Dietary noncompliance and decreased intensive home monitoring were contributory factors. Better ways to predict success or failure are needed if normalization or even near-normalization is a goal of CSII in younger patients with insulin-dependent diabetes mellitus followed up in a nonresearch setting.