Abstract: Objective: To investigate the clinical value of emssion computed tomography(ECT) bone imaging combined with serum prostate specific antigen(PSA) in diagnosing bone metastasis of prostate carcinoma.Methods: Fifty-six cases of prostate carcinoma were reviewed and the correlation between ECT,PSA and bone metastasis was analyzed.Results: The incidence of bone metastasis of prostate carcinoma was 67.8%.The value of PSA between bone metastasis(BM) group and non-BM(NBM) group had significant difference(P<0.01);the value of PSA and the degree of bone metastasis were positively correlated(P<0.01).Conclusions: ECT is highly sensitive to bone metastasis of prostate carcinoma.If PSA is <10 μg/L,the chance of BM is quite small;if PSA is >100 μg/L,LBM is in high suspect.It suggests that if PSA is > 20 μg/L,LECT bone imaging should be performed.