Recent technological advances have resulted in the production of safe subunit and synthetic small peptide vaccines. These vaccines are weakly or non-immunogenic and cannot, therefore, be used effectively in the absence of immunological adjuvants (agents that can induce strong immunity to antigens). Owing to the toxicity of adjuvants, only one (aluminium salts) has hitherto been licensed for use in humans, and it is far from ideal. In this article, Gregory Gregoriadis discusses the use of liposomes as an alternative safe, versatile, universal adjuvant that can induce humoral- and cell-mediated immunity to antigens when administered parenterally or enterally.