Reliable assessment instruments are essential for a new nursing care insurance system enacted in April 2000 in Japan, to ensure the quality of home care. We developed an assessment sheet based on a minimum data set and care assessment, previously developed by the Japan Visiting Nursing Foundation. This article describes the process of testing in practice, validation and revision of the assessment sheet and problem/need areas. One hundred and twelve subjects were initially visited in 48 home care agencies. The same nurse used the assessment sheet for the same client at the initial visit and one month later. After a refinement process, the assessment items and problem/needs areas were simplified. Documentation time for the assessment was significantly shortened. These assessment instruments help development of care plans by identifying client needs, utilization of social resources and evaluation of outcomes.