Background: Occupational stress has been associated with low job satisfaction, poor quality of work performance, organizational inefficiency, high staff turnover, sickness absenteeism, and increased costs of health care. Aim of the study: was to investigate the causes and effects of stress among hospital staff nurses in different hospitals in Zagazig city. Subjects and Methods: Research Design: A cross sectional analytical design used in the study. Setting: El-Ahrar Zagazig General Hospital this affiliated to Ministry of Health hospitals, General surgery hospital and medicine hospital these affiliated to Zagazig university hospitals, and El- Mabara hospital this affiliated to Health insurance hospitals. Subjects: 551 nurse and 511 patients from all study hospitals. Tools of data collection: Two tools were used to collect data. The first was an interview questionnaire sheet to assess the causes of stress among hospital staff nurses. The second tool was questionnaire to measure the effect of stress on nurses' turnover, health status, and patient satisfaction. The results of present study revealed that all nursing staffs in the three hospitals were under stressors. The highest total mean score of stress present in MOH, followed by university hospital and lastly health insurance hospital, 48.8% of the staff nurses scored high effect of the stress on their physical health and the remaining scored moderate effect of the stress (46.8%), the patients in different hospitals were moderately satisfied from nursing care provided to them. Conclusion: Most of study nurse were working under moderate level of stress. Also the stress effected moderately in their turnover and general health, but this stress not effect on patient satisfaction from nursing care provided to them. Recommendation: Stress management program should conducted to all nurses to know how to deal with the stress, further study in other place to asses stress among nurses its causes and effect