Interferon alfa is used to treat various systemic disorders and recently has been suggested as a possible treatment for choroidal neovascularization. We report 10 cases of retinal ischemia associated with the use of interferon alfa for various illnesses. The retinal findings include cotton-wool spot formation, capillary nonperfusion, arteriolar occlusion, and hemorrhage. The retinal complications may sometimes be reversible when treatment is stopped. Our findings emphasize the need to have patients who are receiving interferon alfa therapy monitored for these retinal complications, which may rarely be associated with permanent loss of vision secondary to closure of retinal capillaries.