A follow-up study on 5442 inhabitants (2699 men, 2743 women) was conducted to determine the association between urinary Ca excretion level and mortality of the general population of three different areas of the Jinzu River basin area, namely, non-Jinzu River, mixed, and the Jinzu River water systems, over a period of 6127 d. More than 98% of the subjects were followed completely in each area. In comparison with the low- and high-Ca-excretion groups (cutoff values; 25.1 mg/dL in men, 20.4 mg/dL in women), the mortality rates per 1000 person-years and standardized mortality ratios (SMRs) tended to be greater in the low-Ca-excretion groups than in the high-Ca-excretion groups in both sexes for each of the three areas. Moreover, Cox's hazard ratios in men and women of the three areas exhibited negative values, 0.99 except for men of the mixed water system. These values were statistically significant in both sexes for the Jinzu River water system and in women for the non-Jinzu River water system. We conclude that the life-span becomes shorter as urinary Ca excretion levels become lower.