The human gene MAGE encodes tumor specific peptide antigens and consists of at least 12 families. Some antigens coded by the MAGE genes may be potentially useful for cancer specific immunotherapy. There is, however, so far little information on the expression of these gene families in human esophageal carcinomas. We investigated the expression of MAGE-1, -2, -3, -4, -6, -8, -9, -10, -11, and -12 genes in 24 human esophageal carcinoma cell lines, and in 50 pairs of tumor and corresponding normal tissue specimens from the human esophagus by means of reverse transcription polymerase chain reaction. The expression rate varied from 13% of MAGE-6 and 8 to 79% of MAGE-4 in the esophageal carcinoma cell lines, and from 6% of MAGE-6 to 62% of MAGE-4 in clinical tumor samples. The most frequently and the least expressed gene were the MAGE-4 and MAGE-6 genes, respectively, in both the cell lines and the clinical samples. Forty-seven of the 50 clinical tumors expressed at least one MAGE gene. No significant clinicopathologic difference between the tumor cases was observed, regardless of the presence or absence of MAGE gene expression. The findings of this study thus demonstrated that the MAGE gene family is frequently expressed in clinical samples as well as in the cell lines of human esophageal carcinomas. Therefore, to identify the MAGE gene family may be useful, not only for esophageal tumor specific immunotherapy but for molecular diagnostic usage as well.