The aim of this study was to find out whether there is any relation between the use of preventive health services provided for by municipalities under the Japanese Health Services for the Elderly Act and the demands for in-patient and out-patient care by insured residents aged 40 or older who were covered by the National Health Insurance, eligible for preventive health services under the act, in nine cities within the same catchment area in Osaka Prefecture. Main outcome measures were correlation coefficients between the use of in-patient and out-patient care, and (1) the rate of use of health check-ups, and (2) the cost for preventive health services per resident. Hospital admission rate per 1000 insured persons had a strong negative correlation with the rate of use of health check-ups. The rate of long stay, 180 days or more, per 1000 insured persons was also negatively correlated with the rate of use of health check-ups. There were negative correlations between the rate of use of health check-ups and both the in-patient cost per insured person, and the rate of high in-patient cost, 600,000 Yen or more, per 1000 insured persons. On the other hand, out-patient utilization rate per 1000 insured persons had a positive correlation with the rate of use of health check-ups. However, there was a negative relation between the rate of use of health check-ups and the out-patient cost per insured person because of negative associations between the rate of use of health check-ups and the out-patient days, and cost per case. The rate of high out-patient cost, 60,000 Yen or more, was negatively correlated with out-patient utilization rate per 1000 insured persons. Negative relations were also shown between the cost for preventive health services per resident and the in-patient and out-patient cost per case and per insured person, except out-patient utilization rate per 1000 insured persons. The correlation coefficient between the cost for preventive health services per resident and the total medical cost per insured person was r = -0.779 (P = 0.007). Provision of preventive health services under the Health Services for the Elderly Act may possibly improve health management in the early stage of diseases by detecting abnormalities in health, and that investing in prevention might contribute to reducing the subsequent total demand for medical care.