In our study, a recombinant adenovirus based on the avian adenovirus CELO genome, has been constructed that contains the human interleukin-2 gene. We have shown the production of biologically active recombinant interleukin-2 in vitro (LMH and 293 cells) and in ovo (chicken embryos) infected with recombinant virus CELO-IL2. An increase in the median survival time of C57BL/6 mice carrying B16 melanoma tumors has been demonstrated after multiple intra-tumors injections of the recombinant adenovirus CELO-IL2.