Oncolytic viruses are a new class of immunotherapy drugs that kill cancer cells and stimulate systemic anti-tumor immunity. These viruses selectively replicate in tumor cells, leading to direct cell death and the release of tumor-associated antigens, which can trigger an immune response. The mechanism of action involves viral replication, cell death, and the induction of immune responses through danger signals and tumor-associated antigens. Oncolytic viruses can also enhance the immune system by activating innate and adaptive immune responses, including the release of cytokines and the activation of T cells. The success of oncolytic viruses depends on the balance between viral replication and immune responses. Several oncolytic viruses, such as T-VEC (a modified herpes simplex virus type 1 encoding granulocyte-macrophage colony-stimulating factor), are in clinical trials and show promise for cancer treatment. Challenges in the development of oncolytic viruses include their ability to replicate in cancer cells, the need to avoid immune clearance, and the optimization of viral vectors to enhance therapeutic efficacy. Oncolytic viruses can be engineered to target specific cancer cells, enhance immune responses, and overcome physical barriers in tumors. The development of oncolytic viruses as a new class of cancer therapeutics is an active area of research with significant potential for improving cancer treatment.Oncolytic viruses are a new class of immunotherapy drugs that kill cancer cells and stimulate systemic anti-tumor immunity. These viruses selectively replicate in tumor cells, leading to direct cell death and the release of tumor-associated antigens, which can trigger an immune response. The mechanism of action involves viral replication, cell death, and the induction of immune responses through danger signals and tumor-associated antigens. Oncolytic viruses can also enhance the immune system by activating innate and adaptive immune responses, including the release of cytokines and the activation of T cells. The success of oncolytic viruses depends on the balance between viral replication and immune responses. Several oncolytic viruses, such as T-VEC (a modified herpes simplex virus type 1 encoding granulocyte-macrophage colony-stimulating factor), are in clinical trials and show promise for cancer treatment. Challenges in the development of oncolytic viruses include their ability to replicate in cancer cells, the need to avoid immune clearance, and the optimization of viral vectors to enhance therapeutic efficacy. Oncolytic viruses can be engineered to target specific cancer cells, enhance immune responses, and overcome physical barriers in tumors. The development of oncolytic viruses as a new class of cancer therapeutics is an active area of research with significant potential for improving cancer treatment.