This study was performed to evaluate the clinical symptom, fracture finding, and surgical outcome in children with orbital trapdoor fracture. Forty-four patients with pure orbital trapdoor fracture, under 18 yr of age, were included. Time interval between injury and surgery, length of time for improvement, resolution of ocular motility restriction, and other factors were analyzed in 36 patients who underwent surgery. The median improvement time was 3.5 days for patients (n=8) receiving surgery within 5 days, 18.0 for those (n=19) receiving surgery between 6 and 14 days, and 50.0 for those (n=9) receiving surgery after 15 days (p=0.03). One month after operation, the mean change in supraduction limitation was 3.50±0.53 for patients receiving surgery within 5 days, 2.11±1.24 for those receiving surgery between 6 and 14 days, and 1.67±0.82 for those receiving surgery after 15 days (p=0.04). Three months after operation, the mean change in supraduction limitation was 3.88±0.35, 2.94±1.55, and 2.50±1.38, respectively (p=0.14). In conclusion, trapdoor fracture of the orbit in children must be diagnosed by careful CT evaluation and clinical evidence of entrapment. For patients with severe limitation of ocular motility, early surgery within 5 days of injury leads to more rapid and better postoperative improvement.