Combining attenuated NDV with NK cell therapy may therefore enhance anti-tumor efficacy.<h4>Aim</h4>This study aimed to investigate the synergistic anti-cancer potential of NK cells activated by attenuated NDV against breast cancer cell lines AMJ13 and MCF-7, with emphasis on cytotoxicity, adhesion, and immunophenotypic changes.<h4>Methods</h4>NK cells were isolated from peripheral blood using separation media and 8 μm mesh filtration, followed by expansion in culture with interleukin-15 (IL-15). The gene discussed is IL15; the disease is breast cancer.