Objective To investigate the value of the urinary sarcosine in the diagnosis and prognosis of prostate cancer(PCa). Methods A total of 16 PCa patients, with age ranging from 65 to 89(68.4±10.2)years, diagnosed by prostate biopsy in our department from May 2009 to May 2011, were enrolled in this study. Their blood and urinary samples were collected for detection of sarcosine level by isotope dilution-liquid chromatography mass spectrometry (LC/MS). Electrochemiluminescence assay was used for the detection of serum level of prostate specific antigen (PSA). The results were statistically analyzed with their Gleason scores and with bone metastasis. Results There was significant difference in the total PSA(TPSA) level between the PCa patients with bone metastases [n＝9, (203.95±169.68)μg/L] and without [n＝7, (35.53±35.77)μg/L, P＜0.05], while no difference was found in free PSA (fPSA) level between them [(14.41±11.84) vs (3.92±4.15)μg/L, P＞0.05]. The urinary sarcosine level was significantly higher in the PCa patients with bone metastasis than those without [(1277.67±432.78) vs (494.71±211.35) μg/L, P＝0.018]. There was no significant difference in the serum sarcosine level between different pathological Gleason scores, but urinary sarcosine level was significantly elevated with the increase of Gleason score(P＞0.05). Urinary sarcosin level was correlated with Gleason score and bone metastasis(P＜0.05). Conclusion Urinary sarcosine might be used as a useful tumor marker for the diagnosis and prognosis of PCa.