Many countries are using the strategy of international recruitment to make up for shortages of health professionals to the detriment of health systems in the poorest parts of the world. This study reviewed the potential impact of eight national level and international codes of practice or similar instruments that are being introduced to encourage ethical recruitment in order to protect these countries. Whilst effective dissemination of the instruments is generally in place, support systems, incentives and sanctions and monitoring systems necessary for effective implementation and sustainability are currently weak or have not been planned. If such codes or instruments are to be used to protect developing country health systems, lessons should be learnt from the early adopters; the focus of protecting developing country health systems needs to be emphasised in instruments with multiple objectives; the process of implementing the instruments strengthened; and internal and external pressure needs to be increased to ensure the codes and instruments lead to ethical recruitment and help to protect developing country health systems.