We have studied neuropathologically 200 aged nursing home residents (101 men and 99 women) autopsied between 1976 and 1985. Seventy-three of the 200 showed dementia during life, that is, 27% and 55% of the residents in nursing homes and special nursing homes, respectively. The relative frequencies of SDAT and VD in nursing homes as a whole were the same (34%). The relative frequencies of SDAT and VD in special nursing homes, where usually high concentrations of VD have been noted, were 21% and 52%, respectively. A comparison of the results of our special nursing homes (SDAT:VD = 1:2.5) and nursing homes as a whole (SDAT:VD = 1:1) with those of Barnes and Raskind (SDAT:VD = 2:1) and Rovner et al. (SDAT:VD = 3:1) showed that the frequencies of VD in Japanese nursing homes are considerably higher than those in their American counterparts.