A recombinant Newcastle disease virus (NDV) containing human interleukin-2 (IL-2) gene was generated by applying reverse genetics technique and further evaluated for its suitability to express and deliver IL-2 for cancer therapy. We have further analyzed the ability of rNDV/IL2 to express IL-2 in several human tumor cell lines, including the human breast carcinoma cell line MCF-7, the human colon-adenocarcinoma cell line HT29, and human Jurkat cell line. IL-2 expressed by tumor cells infected with rNDV/IL-2 was stable up till 16 days, at body temperature, and with biological activity. Expression kinetics indicated that the expression level of IL-2 was already high at 24 h after infection and reached the highest level at 48 h after infection. As NDV was proposed as a very promising oncolytic agent in a new age of therapeutic viruses, our data strongly support the application of recombinant NDV/IL-2 virus as an anti-tumor agent.