Survivin (SVV) is a new member of IAP-family (inhibitor of apoptosis, IAP) proteins. It can inhibit apoptosis induced by a variety of factors, and plays important roles during mitosis and cytokinesis of cells. Studies indicated that it is a tumor-specific anti-apoptosis factor. Survivin is expressed during embryonal development but lacks expression in terminally differentiated adult tissues. Interestingly, it becomes reexpressed in transformed cell lines and in a variety of human tumors. Its overexpression is prognostic of tumors and is implicated in the resistance to chemotherapy of tumor cells. SVV may be a new and widely applicable target for gene- and protein-based therapy of tumors.