The ability to retain Volunteers has proved a challenge to many international organizations. This is no exception for many volunteers engaged in international organizations. Volunteers are more intrinsically motivated compared to extrinsic motivation and their need is to make a valued contribution by giving back to the community and skill acquisition. The aim of this study was to establish the factors determining volunteers‟ turnover with a special focus on United Nations National Volunteers in Kenya. Hopefully, the outcome of this study would contribute to greater understanding on various challenges international organizations go through in trying to retain Volunteers. The study adopted a descriptive research design Managers from various UN agencies, and current Volunteers as well as former United Nations Volunteers in Kenya were interviewed with a view to gaining more insight into the factors that trigger a high turnover of such in Kenya. A semi-structured questionnaire and an interview guide will be used for primary data collection. Two theories were used to analyze the data namely Hertzberg‟s Two Factors Theory and Abraham Maslow‟s Theory of Hierarchy of needs. The study revealed that majority choose to volunteer at the UN as a career due to the desire to give back to the society, others choose volunteering because it is the most accessible job, some sees it as an opportunity to take responsibility while others chose volunteering as a career due to personal compatibility. Further, the study found that the rate of turnover among the volunteers at the UN is very high.