Purpose: The purpose of this study was to investigate the impact of the unit-level nurse practice environment on nurse turnover intention in the small and medium sized hospitals. Methods: A cross-sectional study was conducted using a questionnaire survey with 308 nurses in 38 nursing units of 6 small and medium sized hospitals, having over 200 beds and under 300 beds and located in B metropolitan city. Data were collected from July 20 to August 10, 2011. Data were analyzed using hierarchical multiple regression. Results: The mean turnover intention in nurses of small and medium sized hospitals was $3.52{pm}0.53$. Factors affecting turnover intention in the nurses included age, work unit, monthly income, number of night-duties, work hours per day and unit-level nurse practice environment. The unit-level nurse practice environment accounted for 15% of turnover intention when other variables were controlled. Conclusion: The results of the study indicate that nurse turnover intention is associated with the nurse practice environment at the unit level. Small and medium sized hospitals can improve nurse retention and lower turnover intention by changing the nurse practice environment of unit, such as creating better support services and nurse participation in hospital affairs.