Abstract: Objective: To investigate the expression of AMACER and CK34β E12 in small-volume prostatic biopsy tissue and to evaluate their significance in detection of prostatic adenocarcinoma (Cap).Methods: The microamount punctio specimens of 178 prostatic cases, including Cap (n=69), benign prostatic hyperplasia (BPH, n=101), proststatic intraepithelial neoplasia (PIN, n=5) and atypical small acinar proliferation (ASAP, n=3), were stained by immunohistochemical analysis of AMACER and CK34β E12. Results: In the microamount punctio specimens of 178 prostatic cases, AMACER was strongly and diffusely positive(≥+++) in 98.6% of total 69 Cap cases and focally positive(+)in 1 case.In 101 cases of BPH, 17 (15.8%) showed (+) staining and 1 case (1.0%) showed (++) staining. AMAC-ER was negative in all 5 cases of PIN and 3 cases of ASAP. The CK34β E12 was negative in Cap and ASAP cases, it was strongly positive in BPH and PIN cases. Conclusions: AMACER is a kind of spe-cific positive tumor marker for prostatic adenocarcinoma. AMACER combined with CK34β E12 in puncture biopsy of prostate can improve the detection rate of early prostatic adenocarcinoma and the tumors with less than 0.5 ml.