Objective  To study the expression of HBcAg in the spleen tissue of the dead fetus infected by hepatitis virus B(HBV) through maternal  fetal transmission.Methods  40 cases of spleen tissues of dead fetus in the puerperal delivery with HBV were detected for HBcAg by immunocytochemistry(SP).And the detection on HBV in the mother veins before delivery were considered.Results  HBcAg were found positive both single or inclusters form distributed in the plasma of the lymphocyte and the macrophagocyte in the white pulp,marginal zone,red pulp and spleen vessels,but not in the spleen cell nuclei.The HBcAg positive rate is obviously higher in the pleen tissues of the dead fetus delivered by mother with HBV for only one HBVM  + than HBsAg  + HBeAb  + HBcAb  +.But there is not much statistical difference in comparison(  P  >0.005).Conclusions  The positive rate of HBVM in the spleen was not correlated with the HBVM in the pregnant woman veins.HBV maybe copy in the spleen tissues.