The thrombolytic effect of recombinant tissue plasminogen activator was studied in 28 randomly selected rabbit eyes to lyse photochemically induced retinal vein occlusion. Occlusion was confirmed histologically and assessed by fluorescein angiography. Sixteen eyes were treated with recombinant tissue plasminogen activator given intravenously and 12 control eyes were given similar volumes of normal saline solution. Fluorescein angiography was performed before and at various intervals after treatment. Four hours after treatment, the retinal vein was patent in 16 eyes (100%) treated with recombinant tissue plasminogen activator, as opposed to one eye (8.3%) treated with normal saline. The results indicate that tissue plasminogen activator is effective in lysing experimentally induced retinal vein thrombi.