The possible transport of serum γA into saliva was studied in the newborn period. Five infants with erythroblastosis fetalis and undetectable γA in serum or saliva had two-volume exchange transfusions. Serum γA rose to "adult" levels after transfusion, but no detectable γA appeared in serial samples of saliva, as measured by electroimmunodiffusion (EID). The data support the thesis that salivary γA is not transported from the serum and tends to confirm the findings of Haworth and Dilling who previously described the absence of salivary γA following exchange transfusions in newborn infants.