introduction: ocular trauma is considered a health care problem because is an important cause for visual impairment. intraocular foreign bodies are related to activities involving usage of metallic objects, but other materials can be present in the eye and have to be diagnosed and localized. ultrasound biomicroscopy is an adequate subsidiary tool to evaluate an anterior chamber intraocular foreign body. purpose: to characterize nature, localization, dimensions of foreign bodies and associated lesions to the anterior segment using ultrasound biomicroscopy. methods: retrospective clinical study of 7,182 patient's charts submitted to ultrasound biomicroscopy examination between 1999 and 2008, totalizing 59 eyes suspected of anterior segment foreign body. results: five cases presented two foreign bodies, fragments from the same nature, in different locations or not; and three cases had uncountable fragments in the anterior segment. concerning localization: cornea, 11 (26%); conjunctiva, 10 (23%); iris, 10 (23%); lens, 9 (21%); sclera, 5 (12%); corneal angle, 5 (12%); ciliary body, 3 (7%). among the associated lesions, it was identified: corneal perforation in 12 cases, corneal laceration in 2 cases, anterior synechia in 6 cases, traumatic aniridia 1 case, traumatic iridotomy in 3 cases, anterior chamber reaction in 10 cases and rupture of the anterior lens capsule in 4 cases. considering composition: metallic, 21 (50%); non metallic, 20 were glass (48%) and 1 was vegetal (2%). the size of foreign bodies varied from 0.09 to 2.45 mm (average: 0.84 mm). conclusions: ultrasound biomicroscopy is useful to localize foreign bodies in the anterior segment. this imaging method can give orientation about composition, path, and localization of foreign bodies and associated lesions, thus facilitating therapeutic planning prior to intervention, avoiding additional lesions to the eye.