The work presents the results of experimental study of gamma interferon obtained by gene engineering techniques on the basis of Escherichia coli producer strains. The study has revealed that gamma interferon, whose molecular weight is 15 KD, due to intracellular proteolytic degradation shows the absence of some amino acids at the C-end of protein and is electrophoretically homogeneous, while its antiviral, antiproliferative and immunomodulating effects are less pronounced than those of gamma interferon with a molecular weight of 18 KD.