In immunology, an adjuvant refers to any agent that stimulates the immune system and thus, increases the response to a vaccine. Optimal conditions for effective processing of the antigen are provided by the appropriate adjuvants. This book discusses the role of such immunologic adjuvants in diseases such as cancer, their clinical use and their potential future applications. Cancer is often associated with an increasingly impaired immune response against a tumour. Escape mechanisms of the tumour affect the ability of the immune system to build up an effective response against the growing tumour. The roles of such adjuvants in cancer vaccinations are described. Toll like receptors (TLRs) are part of the innate immune system. They are considered as major targets for the development of agonists that could serve as adjuvants and agents of immunotherapy. The development of TLR agonists for clinical use are discussed as well. CpG-ODN (oligodeoxynucleotide) is described as well as how it could be effective as an adjuvant for humoral and cellular immunities. Additionally, a transcutaneous vaccination as an effective approach for the development of tumour vaccines is explained. The development of effective vaccines for malaria, tuberculosis and HIV represents one of the most important scientific public health challenges of our time. Novel concepts in malaria proteins are examined as well as recent advances in the design of synthetic vaccine candidates and antigen delivery systems based on immuno-potentiating reconstituted influenza virosomes. The majority of vaccines presently under investigation represents highly pure recombinant proteins or subunits of pathogens and hence lacks most of the features of the original pathogens. Thus, the development of safe and potent immunologic adjuvants that can enhance and direct vaccine-specific immunity is urgently needed. Aluminium hydroxide (alum) is currently the only vaccine adjuvant approved for human use world-wide. Thus, recent developments in immunology are examined as well as Toll-like receptors and other innate immune receptors. Finally, interleukin-6 plays a crucial role in CFA-augmented immune reactions. Studies that shed light on the involvement of interleukin-6 in the augmentation of immune response by immunologic adjuvants are thus explained.