The pregnant SCID mice and BALB/c mice were intraperitoneally inoculated with mixture of MHV1, MHV3, A59, JHM and euthanized on 1st, 2nd, 5th, 8th, 10th day after inoculation. The blood, liver, placenta of pregnant mice and liver of fetuses were taken, and total RNA of each sample was extracted by RNA extracted kit. Then ,total RNA was transcribed into cDNA by using Mu-MLV reverse transcriptase and the cDNA was amplified by PCR in same tube. The results indicated that MHV was present in the placentas of pregnant mice and the livers of fetuses. The present study demonstrated that transplacental transmission of MHV to fetus was effected by intraperitonesal inoculation of pregnant mice.