Objective:To investigate the value of the plasma transforming growth factor β1 (TGF-β1) level in diagnosis and prognosis of prostate cancer (PCa). Methods: The ELISA kits for human TGF-β1 were used to measure the TGF-β1 level in plasmas. A cohort of 295 consecutive PCa patients in recent more than two years in the First Hospital of Peking University of China was enrolled to the study. Furthermore,55 control subjects were healthy and without evidence of PCa,who were random people that came to the hospital and were identified by prostate biopsy. Results: An age-related frequency chart in-dicated that 99% confidence interval of the difference with PCa was at the age of 53-85 years. The PCa patients aged 53-85 were classified into three groups according to TNM staging. Group A had Stages T0,T1 and T2. Group B had Stage T3 and Group C had Stage T4. Compared with control group,Group A had the lower level of plasma TGF-β1 (P < 0.05),Group B had the higher level of plasma TGF-β1 (P < 0.05) and Group C had the even higher level of plasma TGF-β1 (P < 0.01). According to TNM staging,Group D had Stages T0,T1 and T2 with the normal level of total PSA (tPSA). Group E with the normal level of tPSA had metastasis after resection. Compared with control group,Group D had the lower plasma level of TGF-β1 (P <0.05) and Group E had higher plasma level of TGF-β1 (P < 0.01). Conclusion: The plasma TGF-β1 level decreases at early stage of PCa and increases at later stage of PCa,especially at tumor metastasis after the resection. The plasma TGF-β1 level may therefore be complementary to PSA for PCa prognosis. Objective: To investigate the value of the plasma transforming growth factor β1 (TGF-β1) level in diagnosis and prognosis of prostate cancer (PCa). Methods: The ELISA kits for human TGF-β1 were used to measure the TGF-β1 level in Plasmas. A cohort of 295 consecutive PCa patients in recent more than two years in the First Hospital of Peking University of China was enrolled to the study. Furthermore, 55 control subjects were healthy and without evidence of PCa, who were random people that came to the hospital and were identified by prostate biopsy. Results: An age-related frequency chart in-dicated that 99% confidence interval of the difference with PCa was at the age of 53-85 years. The PCa patients aged 53-85 were classified into Group A had Stages T0, T1 and T2. Group B had Stage T3 and Group C had Stage T4. Compared with control group, Group A had the lower level of plasma TGF-β1 (P <0.05) , Group B had the higher level of plasma TGF-β1 (P <0.0 According to TNM staging, Group D had Stages T0, T1 and T2 with the normal level of total PSA (tPSA). Group E with the Compared with control group, Group D had the lower plasma level of TGF-β1 (P <0.05) and Group E had higher plasma level of TGF-β1 (P <0.01). Conclusion: The Plasma TGF-β1 level decreases at early stage of PCa and increases at later stage of PCa, especially at tumor metastasis after the resection. The plasma TGF-β1 level may therefore be complementary to PSA for PCa prognosis.