Abstract: Objective To detect the expression of apoptosis gene PDCD5 in tissues of normal human kidney, renal clear cell carcinoma, normal bladder and bladder carcinoma, and explore the role of PDCD5 gene in renal clear cell carcinoma and bladder carcinoma. Methods Indirect immunohistochemistry was employed to detect PDCD5 expression in 63 kidney specimens and 42 bladder specimens. Positive expression rates and intensity of PDCD5 protein expression in the kidney tissue were investigated microscopically and by computerized image analysis. Positive expression rate in the bladder tissue was investigated by microscopic observation. Results The results of immunohistochemical staining showed PDCD5 protein overexpression in the renal tubule of normal human kidney tissues and downregulation with the stage increase of renal clear cell carcinoma. PDCD5 protein expression showed statistical significance in tissues of normal kidney and renal clear cell carcinoma in all stages. No obvious PDCD5 expression was detected in the tissues of normal human bladder and bladder carcinoma. Conclusion PDCD5 is an important apoptosis-regulating factor in the occurrence of renal clear cell carcinoma, and its expression is extremely low in tissues of normal human bladder and bladder carcinoma.