This paper examines to what extent and how the data and results of PISA have been used for various education stakeholders and to what extent PISA affect educational policy and practices in Hong Kong. From the point of view of the government, PISA has played an important role in supporting and legitimising government educational reform since 2000. It has supported curricula frameworks and to some extent development and reform from the philosophical and educational viewpoints. However, the mass media and general public seldom went beyond ranking to look at other variables that might inform policy with the exception of some researchers and curriculum developers. Nonetheless, considerable effort has been expended by key researchers in Hong Kong in disseminating information about PISA prior to and after the administration of each assessment and in sharing the Hong Kong results, through such means as press conferences, seminars, international conferences, research and professional development. Experience from the case of Hong Kong suggested that, by keeping international assessment low stake but making good use of it to inform different stakeholders and initiating teacher professional development could be a cost-effective tool to drive educational reform. However, there is a tendency of overuse or abuse of international assessments by making international assessment high stakes, which might create unnecessary pressure for participating schools, teachers and students.