Dual practice - the situation that government health workers are involved in private practice is available in many countries around the world, including developed and developing countries. This is a problem affecting many aspects of access to and quality of health care services as well as the legal and professional relationships in the health system of each nation. How to solve the problem is not entirely the same, depending on the socio-economic conditions of each country. However, the general trend is that the Government does not prohibit dual practice, but manages it by certain regulations. This article reviews some theoretical and practical issues of the dual practice around the world and in Vietnam.