Museums use resources in order to provide public goods and services. The most important sources of income for many museums are budgetary subsidies. Unfortunately, these grants are limited and shrinking. In this context, during the last years the need for sustainable development of museums was stressed. In order to continue to operate, museums were forced to find ways of increasing their own income and keeping their costs under control. Thus museums have begun to use management and marketing strategies similar to those used by private companies. This paper examines the positive effects of international strategy implementation on museums’ sustainability. The first part of the paper explains why it is necessary to reform the traditional management of museums, which its main development directions are, what the sustainable development of museums is and why they should become sustainable. In the second part our research conducted on three museums (Guggenheim, Louvre, Hermitage) shows that international expansion helps museums to increase their sustainability. The international strategy enables museums to increase their revenue, through licensing agreements, reduce their storage costs, highlight their heritage, improve their market image and be closer to consumers. Thus, through a strategy applied until recently only in the private sector, museums can improve their sustainability, but also better fulfill their purpose of serving the society.