A number of tumor suppressor genes, such as hMLM1, p14, p15, p16, GSTP1, RASSF1, COX-2, APC, CDH1, CDH4, DAP-K, THBS1, TIMP-3, RARβ, MGMT, CHFR, DCC, RUNX3, TSLC1, BCL2L10, IRX1, CMDM and UCHL1, are frequently silenced by hypermethylation in gastric cancer [9–12]. The gene discussed is CDH1; the disease is gastric cancer.