We demonstrated that percutaneous peptide immunization by way of skin with impaired barrier function is a simple and noninvasive strategy to generate effective immune responses against tumors. This therapeutic strategy seems to be beneficial for the treatment of skin-associated malignancies, including CTCL, because specific CTLs are considered to be well-induced in lymph nodes that neighbor barrier-disrupted skin (Fig. 3). There remain unsolved issues concerning (1) the ability of cytokines and growth factors to enhance efficacy of this therapy and (2) the time schedule of clinical trials. It was recently shown that application of antigenic protein or its coding DNA to skin with increased permeability yields antigen-specific antibody responses. Because the skin represents an easily accessible site for immunization and vaccination, percutaneous immunization using corneum barrier-disrupted skin is an alternative to injection of CTL-inducing molecules and can readily be exploited for cancer treatment in humans. The effective induction of CTLs suggests that the method that uses barrier-disrupted skin can potentially be applied to treatments of virus and helminth infections with the use of certain antigenic peptides.