The number of people in the world living with HIV is increasing as HIV-related mortality has declined but the annual number of people newly infected with HIV has not. The international response to contain the HIV pandemic, meanwhile, has grown. Since 2006, an international commitment to scale up prevention, treatment, care and support services in middle and lower-income countries by 2010 has been part of the Universal Access programme, which itself plays an important part in achieving the Millennium Development Goals by 2015. Apart from providing technical support, donor countries and agencies have substantially increased their funding to enable countries to scale up HIV services. Many countries have been developing their HIV monitoring and evaluation systems to generate the strategic information required to track their response and ensure the best use of the new funds. Financial information is an important aspect of the strategic information required for scaling up existing services as well as assessing the effect of new ones. It involves two components: tracking the money available and spent on HIV at all levels, through budget tracking, national health accounts and national AIDS spending assessments, and estimating the cost and efficiency of HIV services. The cost of service provision should be monitored over time, whereas evaluations of the cost-effectiveness of services are required periodically; both should be part of any country's HIV monitoring and evaluation system. This paper provides country examples of the complementary relationship between monitoring the cost of HIV services and evaluating their cost-effectiveness. It also summarizes global initiatives that enable countries to develop their own HIV monitoring and evaluation systems and to generate relevant, robust and up-to-date strategic information.