Objective/Hypothesis: To quantitatively evaluate the long-term impact of sinus surgery on paranasal sinus development in the pediatric patient. Study Design: Longitudinal review of eight pediatric patients treated with unilateral sinus surgery for periorbital or orbital cellulitis with an average follow-up of 6.9 years. Control subjects consisted of two groups, 9 normal adult patients with no computed tomographic evidence of sinusitis and 10 adult patients with scans consistent with sinusitis and a history of sinus-related symptoms extending to childhood. Methods: Application of computed tomography (CT) volumetrics, a technique allowing for precise calculation of volumes using thinly cut CT images, to the study and control groups. Results: Paired Student t test analyses of side-to-side volume comparisons in the normal patients, patients with sinusitis, and patients who had surgery revealed no statistically significant differences. Comparisons between the orbital volumes of patients who did and did not have surgery revealed a statistically significant increase in orbital volume in patients who had surgery. Conclusions: Only minimal changes in facial volume measurements have been found, confirming clinical impressions that sinus surgery in children is safe and without significant cosmetic sequelae.