Background: Nurses job performance is severely affected by fatigue increasing rate of medical errors and health care worker injuries and patient safety associated with fatigue and work conditions Aims: To Study the effect of work conditions and fatigue on nurses job performance. Research design: Descriptive correlation of design. Setting: Al Eman general hospital at Assiut. Subject: consisted of (200) staff nurses. Tools:Three tools were used; I: Work conditions Questionnaire (WCQ), II: Piper Fatigue Scale (PFS), and III: Observational Checklist for assessment Nurses Job performance. Results: There was a negative correlation between job performance and fatigue. But a positive correlation between work conditions and job performance. Conclusion: Staff nurses' job performance was affected by level of work conditions and level of fatigue Recommendation: Recognition and motivation from administration to staff nurses, adjust the hours of work and reducing working days during holidays.