This review of published studies on the costs of HIV treatment and care describes some of the recent developments that have influenced these costs in industrialised and industrialising countries, especially within the context of changing drug treatments. Some of the different approaches to estimating the economic impact of HIV infection are briefly presented. The methods used to review the literature are described, particularly the criteria of a scoring system that was specifically developed to systematically screen some of the studies identified. The mean review score for studies dealing with direct hospital costs increased significantly (p = 0.003) over the 3 periods analysed (before 1987, 1987 to 1995, and 1996 and beyond), indicating that the overall 'quality' of studies increased over time. All cost estimates, other than those from non-industrialised regions, were converted to 1996 US dollars using country-specific total health expenditure inflaters and country-specific Gross Domestic Product Purchasing Power Parity converters. A summary of hospital cost estimates over time and by region demonstrated that the costs of treating asymptomatic individuals and people with symptomatic non-AIDS increased over the period, but that the costs of treating individuals with AIDS appears to have stabilised since the late 1980s. As fewer studies could be identified on the costs of community and informal care, indirect productivity costs and population cost estimates, and costs of care for children with HIV infection, all of these studies were reviewed without the use of the scoring system. Finally, the discussion explores the evidence on the global costs of HIV in non-industrialised economies and the affordability of HIV treatment and care. Some suggestions for the direction of future HIV costing studies are also presented. A need remains for good quality cost data. Adequate research effort should be directed to improving the scope and quality of information on costs of HIV service provision around the world.