To share healthcare information and to promote cooperation among healthcare providers and customers (patients) under computerized network environment, a non-profit organization (NPO), named as OCHIS, was established at Osaka, Japan in 2003. Since security and confidentiality issues on the Internet have been major concerns in the OCHIS, the system has been based on healthcare public key infrastructure (HPKI), and found that there remained problems to be solved technically and operationally. An experimental study was conducted to elucidate the central and the local function in terms of a registration authority and a time stamp authority by contracting with the Ministry of Economics and Trading Industries in 2003. This paper describes the experimental design with NPO and the results of the study concerning message security and HPKI. The developed system has been operated practically in Osaka urban area.