During the last 10 years many melanoma antigens recognized by T cells have been molecularly characterized. This review summarizes the main features of these antigens, including both classes I and II HLA-restricted peptides, and describes their classification into diverse groups according to the tissue distribution of the antigens. The different in vitro and in vivo immunogenicity of such antigens is then discussed leading to the conclusion that Melan-A/MART-1 is the strongest among those tested being frequently recognized by patients' T cells both in vitro and in vivo. However, no correlation was found between T-cell response of melanoma patients to Melan-A/MART-1 and clinical response when it was used for vaccination. Data are also presented that suggest, through an ex vivo analysis carried out with tetramers staining of melanoma-specific T cells, that only in a limited number of advanced patients does a specific immune response develop. This response, however, appears unable to effectively counteract metastatic melanoma growth.