Numerical aberrations of chromosomes 8, 11, 12, 17, X, and Y were investigated on fifteen cases of esophageal squamous cell carcinoma using fluorescence in situ hybridization (: FISH) with chromosome specific DNA probes. There were various aberrations in autosomal chromosomes. Trisomy 12 and trisomy 17 were the most common numerical aberrations (found in six cases, respectively), followed by trisomy 11 and monosomy 17 (in five cases, respectively), trisomy 8 (in four cases), tetrasomy 8 and monosomy 11 (in three cases, respectively). In regard to sex chromosomes, all cases except for one showed extra copy number of X chromosome, two signals were found in male and three signals were encountered in female. Loss of Y was found in six cases and gain of Y was shown in two cases. Quantification of nuclear DNA content by flow cytometry was performed using the same materials. Three of fifteen (20 %) revealed DNA diploidy on DNA histogram, but several numerical aberrations were found in all DNA diploid cases by FISH. Comparing the results with clinicopathologic parameters, there is a good correlation between the number of chromosome 8 and lymph node metastasis (p = 0.0089). Numerical chromosome aberrations of esophageal cancer can be detected easily in preoperative status using endoscopic biopsy specimens. FISH analysis correlates with the extent of disease and may be helpful to determine methods of surgical procedure for the patients with esophageal squamous cell carcinoma