Programmed cell death 5(PDCD5)is a new kind of programmed cell death regulation and control gene. PDCD5′s expression is widespread,and evolution is conservative. PDCD5 has the effect of promo-ting a wide variety of tumor cells to apoptosis and inhibiting proliferation,such as lung cancer,liver cancer et al. Several laboratories′ discoveries show that PDCD5′s expression is significantly decreased when in some dis-ease cases,especially in tumor cases. PDCD5,which is related to the clinical relevance of the tumor,has a great clinical value of discovering,diagnosis and treatment of the tumor.