The change in nasalance following adenoidectomy, tonsillectomy and adenotonsillectomy was studied in 44 children. A subjective assessment of each child's naso-pharyngeal airway was made preoperatively based on a questionnaire completed by the parents. There was no significant change in the nasalance of children following adenoidectomy, but there was a significant increase in the nasalance following tonsillectomy (P = 0.02) and after adenotonsillectomy (P = 0.001). There was no relationship between the change in nasalance and the adenoid volume removed at operation. There was good agreement between the parental subjective assessment of the naso-pharyngeal airway and the preoperative nasalance score, with the best correlation in the adenoidectomy group (r = -0.8) and the adenotonsillectomy group (r = -0.7). Nasalance is more closely related to the size of the naso-pharyngeal airway than to the actual adenoid volume, and measurements of nasalance are of no benefit in predicting adenoid volume. Tonsillectomy had a significantly greater effect on nasalance than adenoidectomy, and adenotonsillectomy had the greatest effect. Further studies are needed to relate nasalance to the size of the naso-pharyngeal airway, but it appears to relate well to the subjective assessment of the airway and may be of use in patient selection for surgery.