Abstract: Objective 　To investigate the effect of Ezrin on the proliferation and invasion of human prostat2 ic carcinoma. Methods 　Human prostatic carcinoma cell line PC23 was cultured. A plasmid of a short hairpin RNA targeting Ezrin was const ructed, and it was t ransfected into PC23 cell line. The expression of Ezrin mRNA and protein were examined by RT2PCR and Western blot method respectively. The pro2 liferation was examined by MTT. Flow cytomet ry was used to detect the changes of cell cycle. Transwell test was used to detect the invasion ability of PC23. Results 　RT2PCR revealed that Ezrin shRNA notably down2regulated expression at mRNA level ( P < 0. 01) . Western blot also revealed notably down2regula2 ted expression at protein level ( P < 0. 01) . The proliferation was inhibited after RNAi t reatment . The cell proportion in G2 2M phase decreased f rom (24. 58 ±4. 23) % to (18. 65 ±2. 21) %. The cell propor2 tion in G1 phase increased f rom (58. 69 ±3. 48) % to (66. 54 ±4. 13) %. The invasion ability decreased f rom (38. 6 ±5. 6) to (24. 5 ±2. 7) ( P < 0. 01) . Conclusion 　Ezrin is necessary for human prostatic carci2 noma cell proliferation and invasion. It is probably an important factor to inhibit tumor.