In order to develop and make widely available assistive devices for persons with severe physical disabilities, understanding their needs is crucial. However previous surveys limited to interviews and questionnaires might not reflect their needs properly or fully. Here we report the results of 24-hour monitoring of daily activities and assisted activities for 3 persons with severe physical disabilities to better understand their actual needs of assistive technology objectively. The results showed that two of the participants with severer disabilities spent more time to keep their health levels than persons without disabilities and needed more assists to gather information and to communicate. Gathering information and communicating with telephones, televisions and computers were most of these two participants' social activities. One of them desired for assistive technology to help them more than others keep privacy in these activities. The other participant used a communication aid and mostly satisfied with the status quo, even with the severest handicap of the three. The results suggests that, in spite of the use of public support and availability of certain assistive devices, the demands for developing and distributing new assistive devices still exists in terms of better support, of ADL, of easier maintenance of health, and of more independence in gathering information and communication, for persons with severe physical disabilities.