Objective responses obtained with high-dose in vivo recombinant interleukin 2 (r-IL2) in some leukaemic patients suggest among other hypotheses that blasts might express tumour rejection antigens potentially recognized by cytolytic T lymphocytes. Such antigens have been described in human melanomas and the MAGE-1 gene, coding for a tumour rejection antigen was recently identified. This gene is expressed in various solid tumours, but not in normal cells. We have screened a panel of haematological malignancies by reverse transcription and PCR and we report that MAGE-1 is not expressed in the blasts from 48 patients whereas three cell lines derived from leukaemias express this gene.