Pulmonary complications during standard therapy of chronic hepatitis C with pegylated interferon and ribavirin are rare but connected with wide spectrum of diseases from sarcoidosis to interstitial pneumonitis. The clinical course of that complications is often serious. In this paper, presentation of two patients with chronic hepatitis C with different anamnesis was shown. In the first case, without pulmonary burden, during therapy the features of pneumonitis were developed. In the second case, in patient with sarcoidosis, the antiviral therapy was carried out without important pulmonary aggravation. In reference to these observations and based on available literature, the pathogenetic mechanisms underlying pulmonary complications during this kind of therapy were discussed. Additionally, the scheme of pulmonary diagnostic proceeding in patients certified and then treated with peginterferon and ribawirin was proposed.