We performed a prospective randomized clinical study to compare intravitreal silicone oil vs. gas (20% C3F8 or 30% C4F8) in the management of complicated retinal detachments and vitreous hemorrhage. Despite similar anatomic and visual results, the gas-treated group had significantly more instances of vitreous hemorrhage, late elevated intraocular pressure, and localized retinal detachment as postoperative complications than those receiving oil injections (P less than .05). Silicone oil injections containing less than 3.0 ml contributed significantly to postoperative detachments (P less than .05).