['To assess the clinical value of retinal or choroidal biopsy in establishing a definitive diagnosis directing subsequent management and to assess the risk involved in such surgery.', 'Retrospective noncomparative interventional case series.', 'Thirteen patients with uveitis of suspected malignant or infectious origin. One patient had 2 consecutive biopsies on the same eye.', 'A retrospective review of a 4-year period was undertaken of all those cases in which the biopsy was taken for diagnostic purposes at a single institution.', 'Ability of biopsy to establish a pathologic diagnosis and guide treatment and surgical complications.', 'A transscleral approach was used in 4 and a pars plana vitrectomy approach in 10 of the biopsies. The only operative complication was a retinal break in 1 case. Postoperative events that might be related to the surgery included 1 localized retinal detachment, 2 cataracts, and 1 phthisical eye. The pathologic diagnosis differed from the initial clinical diagnosis in 5 of the 13 cases. The biopsy result directed specific appropriate treatment in 7 of the 13 cases. In the 6 remaining cases, no specific diagnosis was confirmed, but the results of the biopsy were useful in excluding malignancy and in some cases allowing a therapeutic trial.'] Are retinal and choroidal biopsies helpful in unclear uveitis of suspected infectious or malignant origin?