Hepatitis C is a common infection with worldwide prevalence. It has a variable course and can lead to chronic hepatitis, cirrhosis and hepatocellular carcinoma. Until recently &agr;-interferon (IFN-&agr;) was the only effective treatment available. Combination therapy with IFN-&agr; and ribavirin has been found to be more efficacious than IFN-&agr; alone. Various side effects have been ascribed to interferon, such as arthralgias, myalgias, fatigue, and gastrointestinal and neuropsychiatric symptoms. Interstitial pneumonitis is a rare but known complication of IFN-&agr; when given at a high dosage of 6 to 10 million units per day. Ribavirin is associated with dose-dependent hemolytic anemia, cough, dyspnea, rash, depression, and dyspepsia, although a potential role in interferon-induced interstitial pneumonitis has not been described. We describe a patient with an excellent clinical response of chronic hepatitis C to combination therapy with IFN-&agr; at a dosage of 3 million units per day and ribavirin. The patient developed interstitial pneumonitis that resolved after discontinuation of IFN-&agr; and ribavirin. Given that interstitial pneumonitis has previously been reported with high-dose IFN-&agr;, this case suggests that this complication may occur with lower dosages of IFN-&agr;, although a potential role for ribavirin in this disorder at present remains speculative.