For establish a sensitive and specific method to diagnose schistosomasis,we used the PCR and NEST-PCR to detect the Schistosoma japonicum 5D gene encoding an immunogenic miracidial antigen in samples from schistosomiasis patients and animal models.The PCR protocol gave positive re- sults in liver.spleen and stool samples,but the serum from patients and animal models as well as plasma and peripheral blood mononuclear cells from animal models were negative.The results suggest that S. japonicum DNA not exist in peripheral blood.