Objective: Elderly patients often have impaired taste, nausea, anorexia and delayed healing of decubitus. In many of these patients, serum zinc levels are low and they respond to zinc supplementation. To date, no epidemics of zinc deficiency have been reported in Japan. We studied the prevalence of zinc deficiency and its causative factors in a typical local town in Japan. Design: Cross-sectional study. Setting: Nagano Prefecture (central Japan). Subjects and methods: Serum zinc levels were measured in 1009 habitants (18-96 years old) who participated in an annual mass health examination program of the City in 2003. Of all subjects, 86 with low serum zinc (o65 mg/dl) or high zinc (X90 mg/ dl) levels were randomly selected, and a dietary survey using 24-h recalling methods for 2 consecutive days was performed in 2004. Among them, blood was collected in the morning from 50 subjects (26-94 years old). Results: The percentage of those with low serum zinc levels (2.5th percentile of Americans) was 37.9% in the elderly (X60 years old). The age-adjusted prevalence of low serum zinc was 21.1% in the aged population. A positive correlation was detected between zinc intake and serum zinc levels in elderly subjects (X60 years old). Conclusions: The possibility of zinc deficiency in adult inhabitants in central Japan rises with age. The deficiency correlates with dietary zinc intake. Sponsorship: This research was supported by a grant from local government officials in Tomi City (2004) and the funding of Fancl Corporation.