A Dissertation Submitted in Partial/ Fulfilment of the Requirements for Award of the Degree of Master of Business Administration (MBA - CM) Cooperate Management of Mzumbe UniversityThe ambition to conduct this dissertation was due to the increase employees’ turnover in private sector organization in the country. Employee retention has become a major concern for many private organizations in the current scenario. Every organization needs employees who are loyal and work hard with full dedication to achieve the organization’s objective. It is essential for the management to retain its valuable employees who think in favour of the organization and contribute their level best. The contemporary business climate has found an increase of high demand on firms to attract and retain quality employees with technical skills, experience and knowledge. The objective of the study is to investigate the causes and effects of labour turnover in the Oil and Gas industry specifically in the Tanzania Petroleum Corporation Development. In order to achieve this objective, the study employed both primary and secondary data methods. The primary data were collected by using interviews and questionnaires which were distributed to various employees. Secondary data were collected from various sources such as books, journals, circulars and the internet. The data were analyzed and the findings indicate that, managerial controllable factors such as Low salary or inadequate compensation package, unequal treatment of workers, lack of employee involvement in decision making, lack of promotion and recognition, job stress and poor working environment contribute in employee turnover in private sector organization. The general implication drawn from the findings is that, there is no formal retention strategy at the Corporation. This calls for the new initiative by the Corporation to come up with good retention strategy and redesign HRM policies that will achieve positive behavioral, performance and financial outcomes.