Several genes including tumour suppressor genes and DNA repair genes such as hMLH1, RB1, VHL, p15, p16, RASSF1A, MGMT and BRCA1 in human cancers (Herman et al, 1994, 1996, 1998; Merlo et al, 1995; Esteller et al, 1999a; Baldwin et al, 2000; Gras et al, 2001; Nakayama et al, 2001; Yoon et al, 2001) were shown to be epigenetically inactivated by DNA methylation in tumours. The gene discussed is MLH1; the disease is neoplasm.