Molecular characterization of eight gastric cancer cell lines established in Japan are summarized according to the genetic and epigenetic alterations and growth factor status. TMK‐1 poorly differentiated adenocarcinoma cell line harbors mutant p53 tumor suppressor gene and rearrangement of p15^MTS2. MKN‐1 adenosquamous carcinoma line with mutant p53 reveals silencing of E‐cadherin by promoter CpG hypermethylation. MKN‐7 well‐differentiated adenocarcinoma cell line has amplification of c‐erbB2 oncogene and cyclin E gene. MKN‐28 well‐differentiated adenocarcinoma cell line reveals mutations in p53 and APC tumor suppressor genes and silencing of CD44. The MKN‐45 poorly differentiated adenocarcinoma cell line with wild‐type p53 is characterized by homozygous deletion of p16^{CDKN2/MTS1/INK4A} and p15^MTS2, amplification of c‐met oncogene and promoter mutation of E‐cadherin. MKN‐74 derived from moderately differentiated tubular adenocarcinoma has wild‐type p53. KATO‐III signet ring cell carcinoma line has genomic deletion of p53, amplification of K‐sam and c‐met oncogene and mutation of E‐cadherin. HSC‐39 signet ring cell carcinoma cell line harboring p53 missense mutation has homozygous deletion of p16^{CDKN2/MTS1/INK4A} and p15^MTS2, amplifications of c‐myc, c‐met, K‐sam and CD44 gene and mutation in β‐catenin gene.