FIELD : medicine. SUBSTANCE : group of inventions relates to medicine, namely to infectious diseases and pharmacology, as well as the pharmaceutical industry and biotechnology. Pegylated interferon lambda, which has antiviral effect against hepatotropic viruses, is characterized by the fact that its oral bioavailability is at least 10?. Method for producing said pegylated interferon lambda is also disclosed, including the irradiation of a solution of polyethylene glycol with a molecular weight of from about 400 to about 5000燚a with ionizing radiation in a dose of from 1 to 5燤rad, mixing the resulting solution with an interferon lambda solution, freezing and cooling the mixture to a temperature of -10牥C and below and irradiation of the frozen and cooled mixture with ionizing radiation in a dose of 0.1 to 0.5燤rad. EFFECT : group of inventions provides an expansion of the means for the treatment of infectious diseases caused by hepatotropic viruses, the use of which can be used the route of administration of the drug, other than parenteral, and increases the compliance of patients to therapy. 8 cl, 2 dwg, 4 ex, 5 tbl