 Pneumonia is the fourth leading cause of death and frequently occurs in institutionalized elderly people in Japan. Recently, several clinical and experimental studies have reported the importance of vitamin D in the regulation of immune functions and its deficiency is associated with susceptibility to some infections. In the present study, the investigators hypothesize that deficiency of serum vitamin D is associated with development of pneumonia, and supplementation of vitamin D may lower the incidence of pneumonia and prolong survival in institutionalized elderly subjects. 