Objective To raise the early diagnostic accuracy rate for prostatic adenocacinoma (PA). Methods Twenty-one cases of PA were examined by transrectal ultrasonography. The echo reflection of outer and inner gland were observed to distinct the relationship between abnormal sharp hypoecoic and around tissure, especially seminal vesicles. Results 19 cases of PA were confirmed by pathology, the other 2 was hyperplasia of prostate. Conclusion The transrectal ultrasonography has more high specifity and sensitivity than ventri-ultasonography, especially in the cases with small focus PA.