PURPOSE: To describe ocular (specially fundoscopic) changes due to systemic alpha-interferon (IFN) therapy in patients with hepatitis C. This is a prospective, descriptive and observational (non-interventional) study, and its results are preliminary. METHODS: Patients were selected with indication of alpha-interferon therapy for hepatitis C. They underwent ocular examinations before therapy and 1, 3, 6 and 12 months after starting the therapy. HIV patients and those who had a history of previous treatment with alpha-interferon were excluded from the study, but examined. RESULTS: Fifty-one patients were selected from November 1999 to June 2000. The male-to-female ratio was 1.55. The age average was 47 years. The best corrected visual acuity ranged from 20/15 to 20/40. Most of the symptomatic patients complained of foreign body sensation in the eyes, which became more tolerable with time. Complaints comprised flu-like symptoms, joint pain, depression, headache, and general weakness. Ocular findings related to alpha-interferon were: cotton wool spots (3 eyes) and intraretinal hemorrhage (1 eye). One patient died during the study, due to another disease not related to hepatitis, and one patient refused to be examined. CONCLUSIONS: There are retinal vascular changes due to systemic alpha-interferon for hepatitis C. There are no studies in our country describing ocular changes in patients with hepatitis C on therapy with alpha-interferon. General physicians and specially gastroenterologists should pay special attention to this problem, and refer these patients to the ophthalmologist in order to determine and follow any lesion that may be related to the use of this drug.