The state-of-the-art in cost-outcome analysis of assistive technology (AT) is first reviewed, and then the article focuses particularly on the cost aspects of such technology. It elaborates on the concept of 'social cost' as the main indicator of AT economic impact, and proposes methods to compare alternative AT solutions in terms of social cost. A specific instrument for social cost analysis--Siva Cost Assessment Instrument (SCAI)--was designed to help clinicians estimate the economic aspects of providing individual users with AT solutions. The use of the instrument involves: (1) a description of the objectives of the individual AT programme, (2) the establishment of the sequence and timing of all the interventions forming the programme, and (3) the compiling of a cost calculation table for each AT solution. Such a table distinguishes social costs (the sum of all material and human resources mobilised by the intervention) from the financial plan (the actual disbursement of money over time by involved actors). The SCAI tool is not intended as a decision-maker, it is just an informative instrument that, used during clinical assessment, makes clinicians and users aware of the economic consequences of their decisions. The article also explores the possibility of using SCAI to compare different individual AT programmes. Based on a survey of 31 individual AT programmes carried out over a number of years, a first attempt has been made to infer social cost indicators for various categories of AT equipment. The first clear finding is that--not surprisingly--most AT solutions, though very expensive in terms of initial purchase price, lead to considerable savings in social costs due to the reduced assistance burden. In some cases, the savings detected in social costs were in the range 150,000 euros over 5 years. The second major finding is the marked variation in the social costs of different individual cases where similar AT solutions were implemented, suggesting difficulty in establishing repeatable social cost figures for a given device: such figures also depend on the individual context of the implemented AT solution, and on its inter-relationship with the other AT solutions composing the whole programme.