The purpose of the present study was to investigate the role of PTCH1 hypermethylation on gastric carcinogenesis by observing PTCH1 gene methylation and expression in gastric cancer tissues and the gastric cancer AGS cell line, as well as by investigating the effect of the demethylating agent, 5-aza-2′-deoxycytidine (5-Aza-dC), on PTCH1 gene methylation and expression in gastric cancer cells. Here, PTCH1 is linked to gastric cancer.