Alpha-1-antitrypsin (alpha 1AT) is present not only in the normal gastrointestine, but in malignant gastrointestinal tissue as well. We studied the expression of alpha 1AT mRNA in 30 cases of esophageal carcinoma using a Northern blot analysis. In addition, we also examined the expression of matrix metalloproteinase 7 (MMP7) mRNA in the latest 15 cases by reverse transcriptase-polymerase chain reaction (RT-PCR) method to clarify the relationship between the alpha 1AT and MMP7. In 25 of the 30, the expression of alpha 1AT mRNA in esophageal carcinomatous tissue (T) was lower than that in the corresponding normal tissue (N) of the esophagus. The T/N ratio of alpha 1AT mRNA expression showed a significant inverse correlation with the depth of tumor invasion, lymph node metastasis and stage of disease (p=0.042, p=0.0001 and p=0.002, respectively). The T/N ratio of alpha 1AT bad a converse correlation with that of MMP7 (p=0.034). The current study thus suggested that i) the lower expression of T/N expression may be a marker for the biological aggressiveness of esophageal carcinoma, and ii) the reduction of alpha 1AT may be partially correlated with the overexpression of MMP7 in tumor tissue.