In an attempt to obtain a saponin antigen, ginsenoside Rg$_{1}$ of Korean ginseng was condensed with bovine serum albumin through a series of modification in the side chain structure of ginsenoside Rg$_{1}$ to prepare a reactive intermediate $Rg_{1}$ azide. The modification of ginsenoside $Rg_{1}$[1] yielded $Rg_{1}$ decacetate [II], mp 252, $Rg_{1}$ acetate-glycol [III], mp 263, $Rg_{1}$ acetate-trisnoraldehyde [IV], mp 231, $Rg_{1}$ acetate-carboxylic acid [V], mp 282, $Rg_{1}$ acetate-methyl ester [VI], mp 271, $Rg_{1}$ hydrazide [VII], mp 220, and finally a reactive intermediate $Rg_{1}$ azide [VIII].