One hundred senior citizens aged 80 years and over in homes for the aged were evaluated for the incidence of anemia (hemoglobin under 11.0 g/dl), Hb concentration, serum iron, and total iron binding capacity (TIBC). The subjects were classified into different groups according to age distribution (80-84, 85-89, over 90), as well as sex and life activity levels. In the 80-84 year age group, the Hb concentration was 0.5 g/dl higher than that in the other age groups. The Hb values of the male subjects were 1 g/dl higher than the corresponding values for female subjects. Subjects classified as bedridden had Hb values 1.2 g/dl lower than those in the groups that had higher activity levels (p < 0.001). The incidence of anemia was independent of sex and age differences; however, differences in activity levels were significant (p < 0.001). There are 53 patients with some diseases, urinary tract infections, bed sores (over 3 cm diameter), chronic bronchitis, progressive cancers and chronic rheumatoid arthritis, which may be origins of anemia. Seventy six percent of bedridden patients have one or two of the above diseases and 30% of non-bedridden patients have these diseases. The difference was statistically significant (p < 0.001). In the bedridden group, the differences of the mean Hb levels and the rates of anemia in patients with and without disease were not statistically significant (p > 0.1 in both factors). These facts indicate that the bedridden elderly have a high risk of anemia which is independent of some infectious and malignant diseases.