Genetic polymorphisms may modify the effects of environmental risk factors on cancer occurrence. We have recently launched a comprehensive epidemiologic project, HERPACC II (Hospital-based Epidemiologic Research Program at Aichi Cancer Center II), including both lifestyle and polymorphism data, following HERPACC-I which solely concentrated on lifestyle data. As of April 2001, about 3000 samples of DNA are being stored to conduct case-control studies. Genotyping of 46 polymorphisms has been conducted at the laboratory of the Division of Epidemiology and Prevention. Twelve case-control studies and two papers on a new PCR method, PCR-CTPP (polymerase chain reaction with confronting two-pair primers), have been accepted for publication. Significant findings in Japanese were found for 1) gene-environment interaction for esophageal cancer between heavy drinking and aldehyde dehydrogenase 2 (ALDH2), 2) malignant lymphoma risk with methylenetetrahydrofalate reductase (MTHFR) and methionine synthase (MS), 3) interactions between smoking and two polymorphisms, interleukin 1B (IL-1B) and myeloperoxidase (MPO) for Helicobacter pylori infection, and 4) smoking habits with dopamine receptor D2 (DRD2) and IL-1B. Further studies on interactions with polymorphisms will continue to be conducted for Japanese, using larger sizes of samples.