Limited T-cell receptor (TCR) repertoire of tumor-infiltrating lymphocytes has been found in melanoma metastases and spontaneously regressing melanoma. Immunotherapy with INF-alpha/interleukin 2 can induce tumor regression in a proportion of patients with metastatic melanoma. We analyzed the gene expression of the TCR-beta variable (Vbeta) region of tumor-infiltrating lymphocytes from 16 melanoma metastases by subgroup-specific semiquantitative RNA PCR to investigate the influence of immunotherapy on the TCR pattern. In five progressing metastases before or after immunotherapy, no overexpression of Vbeta gene families was detectable, whereas in seven of seven metastases responding to IFN-alpha/interleukin 2 one to four Vbeta gene families were overexpressed. Preferential usage of certain Vbeta gene subgroups in patients sharing the same HLA class I molecules suggests a T-cell response to dominant public epitopes. Analysis of multiple specimens from the same patients gives evidence that this strong oligoclonal T-cell selection is induced or at least augmented by immunotherapy, supporting the functional relevance of this finding.