ackground: Motivation is an important issue for personnel management in health care settings, as it is related to both performance and intention to quit. Objectives: The study was aimed to determine nurses’ working motivation sources and related factors in hospitals. Design: Descriptive study. Settings: A state university hospital and a public hospital in Turkey. Participants: Two hundred and two nurses were randomly selected from each department in a university and in a public hospital. Methods: Data were collected using a socio-demographic questionnaire and the Motivation Sources Inventory and were analyzed using descriptive and inferential statistics. Results: Among five motivation sources, internal self-concept-based motivation was the highest and intrinsic process motivation was the lowest in nurses. There was a significant relation between scores of some motivation sources and managerial experience, income level, satisfaction from the unit, staff roles, and perception of work stress. Conclusions: Intrinsic process motivation, instrumental motivation, and external self-concept-based motivation sources may be improved to increase nurses’ total motivation.