"Dementia with Lewy bodies (DLB)" was proposed at the first international workshop in 1995. It has received much attention since we had proposed "Lewy body disease" in 1980 and "diffuse Lewy body disease" in 1984. In the CDLB guidelines, which were reported in 1996, the clinical and pathological diagnostic criteria for DLB were shown for the first time. At present, DLB as well as Alzheimer's disease (AD) and vascular dementia (VD) are known as the three major dementing illnesses. The second international workshop was held in 1998, and the third in 2003. One of the authors, K. Kosaka, presented a paper on DLB at each international workshop, based on series of our papers which we had reported since 1976. The revised CDLB guidelines will be reported soon. In addition, the fourth international workshop on DLB will be held by Kosaka in Yokohama in 2007. In this article, we review the history, the clinical, therapeutic, neuropathological, neurochemical and molecular biological issues, based on our previous papers and other important reports on DLB.