This story investigated the effects of interferon-alpha-2b (IFN-alpha 2b) on the Optic nerves of 17 adult male Wistar albino rats. Animals were divided into 3 groups: 6 rats (group 1) received 7.5 units (5 mlU/m(2)) IFN-alpha 2b-a normal treatment dose, and 6 (groups 2) received 30.0 units (20 mlU/m(2))-a high dose; 5 rats (control group) received 0.5 mL saline. Test substances were delivered by intraperitoneal injection 3 times a week for 3 weeks with animals under inhalation anesthesia. After the rats were sacrificed, their optic nerves were dissected, sectioned, and examined under an electron microscope. The mean thicknesses of the basal membranes of blood vessels were 86.354 nm in the control group, 104.297 nm in group 1, and 140.181 nm in group 2. Basal membrane changes in IFN groups were dose dependent. Mitochondrial swelling, degeneration, increased diameter of vacuoles, and vacuolization in the cytoplasm of oligodendrocytes and astrocytes were also observed. IFN-alpha 2b has histopathologic effects on blood vessels and cells of the optic nerve.