The authors report five cases of optic neuritis accompanied by secondary impairment of retinal venous outflow producing the clinical appearance of impending or actual central retinal vein occlusion. In four of five cases, intravenous fluorescein angiography showed delayed venous filling with venous dilation and tortuosity. Decreased visual function was entirely attributable to optic nerve involvement because the clinical and angiographic examinations revealed no evidence of capillary nonperfusion, macular edema, or macular hemorrhage. The visual outcome of the patients paralleled that expected with optic neuritis. The authors believe that optic nerve inflammation associated with secondary impairment of retinal venous outflow is a distinct but uncommon entity. Because of its ophthalmoscopic appearance, this variety of optic neuritis may be confused with either papillophlebitis or central retinal venous occlusion in young patients.