The paper presents the results of the authors’ own pilot study of the prevalence of secondary occult hepatitis C virus (HCV) infection after various primary interferon-free (direct-acting antivirals (DAA)) therapy regimens with original inhibitor drugs in real clinical practice. Examinations have been made in 27 patients randomly selected from 261 ones who achieved a traditional plasma sustained virological response at 12 weeks after the end of a DAA therapy cycle confirmed by HCV RNA aviremia.