The purpose of this study was to investigate to potective effects against transmissible gastyoenteritis virus (TGEV) infection in piglets by administration of the TGEV antiserum orally at 5 hrs, 24hrs and 36hrs after birth. five piglets administered the antiserum were experimentally infected with TGEV at four-day-old. Control group were four piglets infected with TGEV only. Serum antibody titers against TGEV were examined by serum neutralization(SN) test, dectection for TGEV or TGEV antigen from feces and small intestines was tested by reverse transcrption-polymerase chain reaction (RT-PCR) and indirect immunoflurescence (IFA). The results obtained were as follows; 1. The piglets administered the TGEV antiserum showed higher antibody titers than those of control group and sustained during the experimental period. 2. The detection rate of TGEV in feces and small intestines by RT- PCR were 24.5% and 20.0% in TGEV antiserum treated group and 44.0% and 75.0% in control group, respectively. 3 The detection rate of TGEV antigen in the small intestine by IFA were 26.7% in TGEV antiserum treated group and 75.0% in control group, respectively. It was concluded that oral administration of antiserum against TGEV to piglets was effective in preventing TGEV infection.