The home management of chronic disability in the elderly often relies upon the receipt of family. These caregivers have been shown to experience a considerable burden in providing day-to-day care. It is important that identifying problem areas may result in the need of consider alternatives for the care of an elderly person, identify and mobilize existing community resources to relieve some of the "cost". We studied the reliability and validity of a Japanese version of the Cost of Care Index (CCI) which was originally developed by Kosberg et al as a case management tool in the assessment of caregivers. Our subject consisted of 27 cases with dementia (mean age 74.5 years), and 15 cases of patients with neurological disorders without dementia (80.7 years), and their caregivers. The test-retest reliability and internal consistency were very good; the coefficient of correlation between CCI scores at the two interviews was 0.83, the coefficient of internal consistency was 0.92. CCI scores correlated significantly with ADL-20 scores, DBD score and caregivers' SDS scores; r = -0.48, r = 0.46 and r = 0.36, respectively. Our results indicate that the CCI is highly reliable, and may be useful for assessment caregivers' burden.