Using comparative genomic hybridization (CGH), we investigated copy number aberrations in 29 esophageal squamous cell carcinoma (ESC) cell lines. All lines displayed numerous chromosome imbalances. The most frequent losses were observed on chromosome 18q (65.5%), Xp (48.3%), 3p (44.8%), 4q (44.8%), 8p (41.4%), 11q23–25 (34.5%) and 4p (27.6%), whereas the most common copy number gains were noted at 8q (86.2%), 3q (82.8%), 5p (69%), 7p (69%), 20q (65.5%), 9q (55.2%), 11q (55.2%), 1q (48.3%), Xq (44.8%) and 18p (37.9%). High‐level gains (HLGs) were detected at 3q26 (9 cases), 8q23 (6 cases), 5p14–15 (6 cases), 18p11.2–11.3 (6 cases), 3q27–28 (5 cases), 5p13 (3 cases), 7p14–15 (3 cases), 20q12–13 (3 cases), 11q13 (3 cases), 14q21 (2 cases), 20p11.2 (2 cases), 13q32 (2 case), and 1q32 (1 case). Among them, HLGs of 1q32 have been reported in other types of cancer, including glioblastoma and breast cancers. We successfully narrowed down the smallest common amplicon involving 1q‐gain to the genomic segment between D1S414 and D1S2860 by fluorescence in situ hybridization (FISH). Southern and northern blot analysis clearly demonstrated that ATF3, human activating transcription factor‐3 and CENPF, centromere protein F, mapped within this region, were significantly amplified and over‐expressed in 1q32 amplicon.