This course describes the definition and the application of the system thinking in public health and describes the tools to apply it in health services research. It presents the background of the system theory and the precursors of systemic thinking. Also, the definition and the characteristics of the system and the application of the system thinking in public health.   The course will describe tools to conduct health systems research from a system thinking perspective. It reviews both theoretical and practical applications of these tools in the literature, as each has strengths and weaknesses. The purpose of this course is to enable students to be familiar with the system thinking, its application in public health and health services research.