Galacto-oligosaccharides (GOS) is composed of a chain of 1~n galactose units with a sucrose terminal unit, which has many useful biological activities, especially immune activity. However, it is still difficult to total synthesis of GOS. In this year, I successfully accomplished stereoselective synthesis of α-GOS (n=1~8) with boron-mediated aglycon delivery (BMAD) method, which is developed in our lab for the stereoselective synthesis of 1,2-cis glycosides. The most effective α-GOS found in the evaluations will be used as lead compounds for vaccine adjuvants to stimulate human immunity and for therapeutic agents in the future.