Salmonella typhimurium expressing SipB160/IFN-γ (S. typhimurium [IFN-γ]) efficiently secreted IFN-γ in cells. S. typhimurium (IFN-γ) invaded the melanoma cells and induced cytotoxicity. S. typhimurium (IFN-γ) inhibited tumour growth in mice bearing B16F10 melanoma in natural killer cell-dependent manner. S. typhimurium (IFN-γ) exerted little toxicity to normal mouse tissues with no observable adverse effects. S. typhimurium (IFN-γ) did not trigger stable anti-tumour immunity but triggered direct tumour cell killing in mouse models.