Non-ionic surfactant vesicles (niosomes), like their phospholipid liposome counterparts, have shown promise as immunoadjuvants and enhance both the humoral and cellmediated immune responses to a variety of antigens (Brewer and Alexander, 1992, 1994; Hassan et al., 1996). The adjuvant activity has been attributed in part to the temporary depot action of the niosome suspension at the site of injection (Brewer and Alexander, 1992, 1994), the avid uptake of antigen-containing vesicles by macrophages (Fidler et al., 1980; Poste et al., 1980) which may be followed by enhanced antigen processing and presentation to T cells (Brewer and Alexander, 1992, 1994) and to the surface activity of the non-ionic surfactant components. Surfactant action is thought to denature and renature the antigen (Boggs et al., 1985); the antigenic tertiary structure may thus be altered, allowing hidden epitopes to be presented to the immune system.