This study concerns 50 patients with blow-out fractures of the orbital floor, including 15 children, and was designed to evaluate the influence of age on clinical presentation and postoperative results. Fourteen of the 15 children were found to have a trap-door fracture. This type of fracture was not found in adults, who usually present with a large "open-door" fracture. In trap-door fractures, orbital tissues are liable to become trapped and even strangulated. It is therefore suggested that young patients with severely restricted eyeball motility, an unequivocal positive forced duction test, and findings indicating blow-out fracture of the orbital floor on CT, should undergo operative treatment as soon as possible after injury. A "wait and see" policy, keeping the patient under observation, seems to be appropriate for blow-out fractures in adults. Surgical treatment is recommended only in those adult patients who demonstrate impairment of vertical eyeball motility within the mainfield of view after the haemorrhage and oedema have resolved and in whom change in motility is no longer seen and Hertel measurements have stabilized.