The aim of this investigation was trying to identify the genes differentially expressed in esophageal cancer. By combining suppression subtractive hybridization (SSH) with reverse Northern high density blots, a gene named EC45 was obtained, which dramatically overexpressed in 70% esophageal cancer (18/26). EC45 was mapped to 3p12-3p11.2 by radiation hybrid mapping (RH mapping). The putative full length EC45 cDNA (1987 bp) was identified by cDNA libraries screening of esophageal cancer. EC45 encoded 204 amino acids, and it shared a 100% similarity with ribosomal protein L15 (635 bp, mRNA) in ORF, but no similarity in 5' UTR or 3' UTR. Northern blot panel of multiple adult human normal tissues showed EC45 distributed in almost normal tissues tested. All these data suggested that EC45, encoding ribosomal protein L15 and overexpressing in esophageal cancer might play a possible role in carcinogenesis of esophagus.