A total of 83 children and teenagers underwent endoscopic nasal and sinus surgery. Six patients had surgery for choanal atresia (4) and adenoid hypertrophy (2) and will only be briefly mentioned. Seventy-seven children and teenagers underwent endoscopic sinus surgery for acute and chronic sinusitis, choanal polyposis, and nasal polyposis with a minimum 2-year follow-up. One hundred thirty-three ethmoidectomies, 37 sphenoidotomies, and 119 maxillary antrostomies were performed. Subjective evaluation of the sinus surgery patients indicated that 38% of patients were cured and 55% improved during an average of 3.5 years of follow-up. The number cured and number improved are lower and higher, respectively, than in other reports of results because of the longer follow-up and patient selection. In addition, objective data were obtained on 34 patients with a second- or third-look procedure 2 weeks to 2 months after surgery. These examinations found significant granulation tissue, and almost 50% of patients had at least one maxillary ostia closed. Long-term objective results, however, are not available to determine whether the ostia remained closed. Problems with healing in children's endoscopic sinus surgery are unpredictable compared those in adult surgery because postoperative debridement and examination are often difficult to perform, thus allowing tissue to heal without control. In this series, other factors such as the increased risks of cystic fibrosis, allergy, and immunodeficiency were also more prevalent and compromised healing.(ABSTRACT TRUNCATED AT 250 WORDS)