To determine the relationship between tonsillitis, tonsillectomy and abnormalities in body weight, we have analyzed pre- and post-operative weights in a population of 55 children who underwent adenotonsillectomy in our department. Pre-operative mean weight was 9.8% heavier than the standard mean normal weight for age and post-operative mean weight was 22% greater than standard mean weight for age. The mean weight gain during the follow-up period was 12% greater than that which would be normally expected (p < 0.001). This study suggests that children undergoing tonsillectomy are slightly heavier than their peers and that following the procedure this discrepancy increases.