BACKGROUND: A certain diagnosis, as soon as possible, is indispensable in children with intraocular lesions, the presence of retinoblastoma always being a possibility. PATIENTS: From our casuistic of 418 children since 1970 and from the literature, we currently adopt the following attitude. Where the media are clear, a drawing and fundus photographs are made. Echography is performed in all cases. Ultrasound biomicroscopic examination is carried out in all lesions where involvement of the anterior segment is suspected. RESULTS: Where echography shows no calcifications, computed tomography (CT) is indicated. CT may also enable a possible lesion extension, particularly to the optic nerve, to be studied. CONCLUSIONS: Magnetic resonance imaging (RMI) is the procedure of choice for evaluating secondary retinal detachment, massive extension of retinoblastoma and for detecting any early involvement of the pineal gland (pinealoblastoma), or any other associated lesion. In case of unilateral unifocal sporadic retinoblastoma, however, no CT or MRI is performed, except where there is a suspected extension into the optic nerve or the orbit. Echography remains the most economical, rapid and safest means of diagnosis even in difficult cases.