Adamantylamide L-alanyl-D-isoglutamine (AdDP) is a synthetic adjuvant which belongs to the family of the desmuramyl peptides. AdDP exerts its adjuvant properties when it is administered either by the parenteral or by the mucosal route, leading to the elicitation of strong humoral responses at both the systemic and the mucosal levels. However, very little is known about the effect of AdDP on cellular immunity. Here we demonstrate that AdDP is able to stimulate cellular responses, which are characterized by the release of gamma interferon by CD8+ T cells when they are restimulated with a major histocompatibility complex class I-restricted peptide and strong in vivo lymphocyte-mediated cytotoxic activity. The capacity of AdDP to stimulate the elicitation of both cellular and humoral adaptive responses makes this adjuvant a promising tool for the development of mucosal vaccine formulations.