There are significant differences in the some breast milk concentrations of immunoproteins between the mothers in Hanoi and mothers in Hochiminh: the levels of lysozyme and IgA in the breast milk of Hochiminh's mothers were higher markedly than that in the Hanoi's mothers; in contrast, the levels of lactoferrine in the breast milk of the Hanoi's mothers was higher than in that of the Hochiminh's mothers.