[Excerpt from authors]Background:In this paper, we aim to quantify the contribution of international health volunteers (IHVs) to the health workforce in sub-Saharan Africa and to explore the perceptions of health service managers regarding these volunteers. Conclusion: We estimate that not more than 5000 full-time equivalent international health volunteers were working in sub-Saharan Africa in 2005, of which not more than 1500 were doctors. A distinction should be made between (1) secular medical humanitarian NGOs, (2) development NGOs, and (3) volunteer organizations, as Voluntary Service Overseas (VSO) and United Nations volunteers (UNV). They have different views, undergo different trends and are differently appreciated by government officials. International health volunteers contribute relatively small numbers to the health workforce in sub-Saharan Africa, and it seems unlikely that they will do more in the future. In areas where they play a role, their contribution to service delivery is sometimes very significant.