A number of European studies have attempted to assess the treatment and care costs of people with HIV infection or AIDS. However, because of the different methods used, the various cost estimates produced are difficult to compare. This paper reviews several European HIV-AIDS costs studies and outlines the differences in methods used and where better approaches to cost estimation could have been adopted. The application of a standardised cost framework to new cost studies would improve the basis for making cost comparisons of models of care in different sites and countries and the identification of actual (rather than methodological) variations in costs across sites. The final part of the paper provides a discussion of the development and application of a standardised framework for assessment of the costs of HIV-AIDS treatment and care in Europe.