The health services system of Timor-Leste (T-L) will, by 2015, add 800 physicians, most of them trained in Cuba, to the 233 employed by the national health system in 2010-2011. The need for more physicians is not in discussion: poor health indicators, low coverage and utilization of services, and poor quality of services are well documented in T-L. However, the choice of this scaling-up, with a relatively narrow focus on the medical workforce, needs to be assessed for its relevance to the health profile of the country, for its comprehensiveness in terms of other complementary measures needed to make it effective. This article discusses the potential effects of the rapid scaling-up of the medical workforce, and the organizational capacity needed to monitor the process and eventually mitigate any deleterious consequences. The analysis is based on a review of documentation collected on site (T-L) and on interviews with key-informants conducted in 2011. We stress that any workforce scaling-up is not simply a matter of increasing numbers of professionals, but should combine improved training, distribution, working conditions, management and motivation, as a means towards better performing health services' systems. This is a major challenge in a context of limited organizational and managerial capacity, underdeveloped information systems, limited training and research capacity, and dependency on foreign aid and technical assistance. Potential risks are associated with funding the additional costs of recruiting more personnel, associated expenditures on infrastructure, equipment and consumables, the impact on current staff mix, and the expected increased demand for services. We conclude that failing to manage effectively the forthcoming "great leap forward" will have long term effects: formal policies and plans for the balanced development of the health workforce, as well as strengthened institutions are urgently needed. © 2013 Elsevier Ltd. All rights reserved.