Interferons are glycoproteins that bind to cell-surface receptors and lead to anti-viral, anti-proliferative, and anti-angiogenic properties. Interferons have been used successfully in many different diseases throughout medicine, and recently success has been demonstrated for the treatment of ocular surface neoplasias. Traditional treatment for corneal and conjunctival intraepithelial neoplasia and squamous cell carcinoma includes surgical excision and adjunctive cryotherapy. The use of chemotherapeutic agents, including interferon alfa 2b (IFN a2b), mitomycin C (MMC) and 5-fluorouracil (5-FU), has limited the need for extensive surgical manipulation of the ocular surface and potentially decreases recurrence rates. This article will focus on the use of IFN in the treatment of corneal and conjunctival intraepi-thelial neoplasia and squamous cell carcinoma.