A history of poor weight gain can often be elicited in young children with chronic upper airway obstruction resulting from adenotonsillar hypertrophy. A series of 41 consecutive children under 3 years of age, who underwent inpatient adenotonsillectomy, were reviewed for changes in weight and height. Thirty-seven patients had adequate long-term followup. Of these, many had dramatic improvements in growth after adenotonsillectomy. Indications for surgery in this group were recurrent infection in three patients (7%), unilateral tonsillar mass in one patient (3%), and upper airway obstruction in 37 patients (90%). A clear history of sleep apnea was elicited in 59%. At the time of surgery, 19 of 41 patients (46%) were of the fifth percentile or lower for age-corrected weight. The inpatient hospital stay averaged 3.2 days. The postoperative complication rate was 27%, with postoperative stridor as the most common complication. After surgery, 28 children (75%) showed a change to a higher percentile for weight. Twenty-four (65%) had percentile changes of 15% or more. This change is significant according to results of the Wilcoxon signed-rank test (p < 0.001). We conclude that a relationship exists between improved growth rate and adenotonsillectomy in our study group. The rapid improvement in growth appears to be most obvious in children with upper airway obstruction resulting from adenotonsillar hypertrophy. Upper airway obstruction (including andenotonsillar hypertrophy) should be suspected as a possible cause in the workup of children with suboptimum growth.