Background: Decision making is the heart of all administrative and managerial functions. Managers make many decisions as a part of their daily work by different styles and those decisions and styles are affected by many factors. Aim: This study aimed to assess the factors affecting decision-making among nurse managers and its relation to decision-making styles. Material and methods: A descriptive correlation research design was utilized with a sample of 85 nurse managers who were working in Port Said hospitals which affiliated to Ministry of Health. Data was collected from November 2014 to January 2015.Tools of data collection: A personal and job characteristics of the participants, factors affecting decision making questionnaire and general decision-making style inventory (GDMS) were used. Results: The study findings revealed that less than half (42.4%) of nurse managers were influenced by the factors affecting decision making. The highest mean score was for process factors (79.4±13.0), meanwhile the lowest mean score was for individual factors (72.9±13.7). Additionally, the highest mean score was for avoidant style (18.2±3.7), while the lowest mean scores was for rational style (10.5±2.3). Conclusion: There was a statistically significant correlation between factors affecting decision making and all general decision-making styles except the intuitive style. So the findings pointed to create nurse managers abilities related to decision making through educational programs. Also, further researches are suggested.