Differentiated embryo-chondrocyte expressed gene 1 (DEC1), as a bHLH transcriptional factor, plays important roles in cell differentiation, proliferation, and apoptosis. The expression of DEC1 and its role in human gastric cancer are unknown. This study was designed to characterize the DEC1 gene profiling of human gastric cancer tissues. The expression of DEC1 in gastric cancer tissues was analyzed by cDNA microarray, reverse-transcriptase polymerase chain reaction (RT-PCR), Western blot, and immunohistochemical studies. Microarray assay demonstrated that DEC1 was one of the upregulated genes in gastric cancer when compared with normal tissues. The expression of DEC1 mRNA was increased in gastric cancer as determined by RT-PCR. An increased DEC1 protein expression in gastric cancer was verified by Western blot analysis. Immunohistochemical studies showed that the 83.02% gastric cancer tissues (44/53) were stained positive for DEC1. The DEC1 expression was increased during the tumor progression from well differentiated (50%, 4/8) to moderately differentiated (76%, 13/17), and poorly differentiated (96%, 27/28) tumor tissues. In contrast, a weak staining for DEC1 (low expression) was observed in 10 % normal tissues (1/10). Statistical analysis found a significant correlation between increased DEC1 expression and poorly differentiated cancer tissues. These data characterized DEC1 expression in gastric cancer and identified a correlation between upregulation of DEC1 expression and differentiation of gastric cancer, suggesting that DEC1 may play an important role in the differentiation and progression of gastric cancer.