The present study was undertaken to obtain evidence as to the congenital sensitization to food in humans. Egg white antigen titres were measured by the PCA test in following specimens such as mother's blood, newborn infant's blood, amniotic fluid, meconium and first voided urine. Complete antibody titres against egg white determined by the BDB test in above mentioned specimens. Incomplete antibody titres against egg white were demonstrated by the method which was devised by applying Coombs reagent to usual BDB test in above mentioned specimens. 1) Egg white antigen was demonstrated in high titres in the cord blood, the amniotic fluid and the meconium, while it was never observed in the mother's serum. Furthermore, it was interesting to note that it was demonstrable in the first voided urine in over half of the newborn infants. 2) In ten cases in which all samples were drawn at the same time and examined, egg white antigen was not detected in the mother's blood. However, it was discovered in over half of the samples of cord blood, amniotic fluid, and newborn infant's urine. 3) Complete antibody against egg white was markedly evident in the amniotic fluid, moderately exhibited in the mother's blood and in the cord blood, and only slightly apparent in the newborn infant's blood. In addition, complete antibody was not observed in the first voided urine and the meconium. 4) Complete antibody titres against egg white in the amniotic fluid were compared with those in the mother's serum of the same subject. It was shown that there was no correlation between them, and frequently complete antibody titres were far high in the amniotic fluid, when they were absent or extremely low in the mother's blood. 5) Incomplete antibody against egg white was moderately demonstrable in the mother's blood, the cord blood, and the newborn infant's blood, while it was observed only in few cases of the amniotic fluid. Furthermore, incomplete antibody was not demonstrated in the first voided urine as well as the meconium. 6) Incomplete antibody titres against egg white in the mother's blood were compared with those in the cord blood of the same subject. It was shown that there is no correlation between them, and occasionally incomplete antibody titres in the cord blood were far higher than those in the mother's blood. 7) It was evident that a parallelism seemed to exist between complete antibody titres against egg white, lactalbumin and soybean in the amniotic fluid. From these results, the following was considered: 1) Food antigen taken by the mother was not only readily transferred into the fetus, but also into the amniotic fluid, meconium and newborn infant's urine. 2) Both, complete antibody against egg white in the amniotic fluid as well as incomplete antibody in the cord blood were not always derived from the mother's serum, but at least a part of these might include the antibody which was produced by the fetus. 3) Some fetus may be congenitally predisposed toward the production of antibodies against foods transferred from the mother while others are not.