Multiple myeloma idiotypic protein is clone‐specific and therefore represents an ideal tumour antigen for immune targeting. In this study we determined whether a synthetic peptide corresponding to the autologous idiotypic VH CDR3 sequence could elicit peptide‐specific immune responses in a patient with IgA myeloma. Not unlike B‐cell lymphoma, the immune repertoire of the patient contained T cells capable of mounting proliferative and cytotoxic responses to antigen‐presenting cells loaded with the CDR3 peptide. Furthermore, the T cells were also able to secrete interferon‐γ upon peptide rechallenge. Antigen recognition by peptide‐primed T cells was MHC dependent and could be blocked by antibodies to both monomorphic MHC class I and class II molecules. These results therefore indicate the presence of T‐cell epitopes on the VH CDR3 sequence. In addition, CDR3 peptide‐primed T cells were also able to mount similar immune responses when rechallenged with the intact IgA idiotypic protein, suggesting that functional T‐cell epitopes had been derived from the CDR3 sequence of the idiotypic protein. Our results therefore provide a new perspective to the immunogenicity of the idiotypic protein in myeloma.