Considerable effort has been made to estimate the global resource requirements of scaling-up HIV/AIDS and tuberculosis (TB) interventions. There are currently several medium- and long-term global estimates available. Comprehensive country specific estimates are now urgently needed to ensure the successful scaling-up of these services. This paper reviews evidence on the global resource requirements of scaling-up HIV/AIDS and TB interventions. The purpose of this review is to summarise and critically appraise the methods used in the global estimates and to identify remaining knowledge gaps, particularly those relevant to country level estimation.