The combination therapy with pegylated interferon alpha and ribavirin has increasingly prescribed for chronic hepatitis C. Although many side effects of interferon such as flu-like symptoms, gastrointestinal and neuropsychiatric symptoms are well known, only several cases of interferon-induced pulmonary toxicity have been reported. Interferon-induced pulmonary toxicity usually develops from 2 weeks to 12 weeks after treatment for HCV infection. Diagnosis is commonly based on clinical findings such as a dry cough, dyspnea, hypoxemia, and a restrictive pattern in pulmonary function testing, bilateral diffuse parenchymal infiltrations, histopathological findings of interstitial pneumonitis, and exclusion of any other causative agents. Prompt withdrawal of the drug is the cornerstone of treatment. We report a case of PEG-IFN alpha-2a induced pulmonary toxicity in a 50-year-old male patient with hepatitis C. To our knowledge, this is the first case of pegylated interferon alpha-2a induced pulmonary toxicity in Korea.