Lung cancer has an especially high incidence rate worldwide, and its resistance to cell death and chemotherapeutic drugs increases its intractability. The vaccinia virus has been shown to destroy neoplasm within a short time and disseminate rapidly and extensively as an enveloped virion throughout the circulatory system, and this virus has also demonstrated a strong ability to overexpress exogenous genes. Interleukin-24 (IL-24/mda-7) is an important cytokine that belongs to the activating caspase family and facilitates the inhibition of STAT3 when a cell enters the apoptosis pathway. In this study, we constructed a cancer-targeted vaccinia virus carrying the IL-24 gene knocked in the region of the viral thymidine kinase (TK) gene (VV-IL-24). Our results showed that VV-IL-24 efficiently infected and destroyed lung cancer cells via caspase-dependent apoptosis and decreased the expression of STAT3. In vivo, VV-IL-24 expressed IL-24 at a high level in the transplanted tumour, reduced STAT3 activity, and eventually led to apoptosis. In conclusion, we demonstrated that vv-IL-24 has the potential for use as a new human lung cancer treatment. (C) 2016 Elsevier Inc. All rights reserved.