Certain novel compositions of the adjuvant saponin QS-21 having improved properties are disclosed. The compositions of the present invention are designed (1) to minimize the lytic effects of QS-21, (2) to improve the tolerance of QS-21 containing formulations in humans or other animals, (3) to stabilize the QS-21 from alkaline hydrolysis and/or (4) to maintain the high adjuvant potency of the QS-21 product. These compositions may be employed with vaccines comprising proteins or peptides, polysaccharides, lipids, or nucleic acids.