Objective: To analyze the different factors affecting the outcome of transnasal endoscopic repair of choanal atresia (CA) in children., Design: Retrospective study., Setting: Academic tertiary care children's hospital., Patients: Eighty patients (48 girls and 32 boys) aged 3 days to 17 years (mean age, 3 years 8 months) who presented with unilateral (n = 53: 37 right, 16 left) or bilateral (n = 27) CA and underwent surgery between September 1996 and December 2005., Intervention: All patients underwent transnasal endoscopic surgery with telescopes and a microdebrider. Nasal tubes in neonates and nasal packing in older children were removed after 48 hours. Systematic endoscopic revision was performed under local or general anesthesia a week after surgery. Patients were then clinically and endoscopically monitored for nasal obstruction and healing for a mean follow-up of 43 months., Results: A total of 30 patients presented with associated malformations: 9 with CHARGE (coloboma, heart disease, choanal atresia, retardation of postnatal growth()and mental development, genital hypoplasia, and ear anomalies), 1 with Treacher-Collins syndrome, 1 with Kabuki syndrome, 1 with facial cleft, 1 with Down syndrome, 12 with nonsyndromic malformations, and 2 with 22q11 microdeletion. Three children had heart malformations not related to CHARGE association. One child had a congenital nasal piriform aperture stenosis. Twenty-four children had undergone previous surgery; 10 underwent a second procedure with success. Gastroesophageal reflux disease (GERD) was systematically treated in cases of restenosis. Topical mitomycin C was used in 3 patients with relapse. Two patients underwent laser treatment to reduce stenotic scarring. Of the 10 patients who needed revision surgery, 6 had bilateral CA, and 4 had unilateral CA. Age younger than 10 days and presence of GERD increased the chances of restenosis (P = .03). Postoperative stenting negatively affected the outcome. Associated anomalies and previous surgery had no effect on outcome. The bony nature of the CA and bilaterality were not significant (P = .08). However, surgeon learning curve was an important element positively influencing the results (P = .04)., Conclusions: Transnasal endoscopic repair of CA is a safe and successful technique. Predictive factors of restenosis are the presence of GERD, age younger than 10 days at the time of surgery, and insufficient postoperative endoscopic revision. However, previous surgery and associated malformations are not predictive of a poor surgical outcome.