Starting in the late 1980s a major collaborative effort has been carried out in Japan to increase knowledgeabout factors contributing to mortality from cancer and circulatory disease. This Japan Collaborative CohortStudy (JACC Study) is sponsored by the Ministry of Education, Science, Sports and Culture of Japan(Monbukagakusho) and has contributions from 45 areas of the country. With Drs Kunio Aoki and YoshiyukiOhno as leading figures in this endeavour, the cohort now covers more than 100,000 participants enrolled atvarious centers located from Hokkaido in the North to Kyushu in the South. To collect epidemiological informationat baseline, a self-administered questionnaire was used. Follow-up up was to 2003 in the majority of cases anda total of 17,404 deaths were registered, the five commonest sites of cancer development being the lung, stomach,liver, pancreas and colon in men, and the stomach, lung, liver, colon and pancreas in women.