Background: Workplace bullying is a social and organizational problem within the health care system; it has several adverse effects and closely associated with nurses' job performance. Aim :The study aimed to assess the effect of workplace bullying on nurses' job performance. Research design: Descriptive correlational design was utilized to meet the aim of this study. Setting: This study was conducted in Intensive Care Unit at Benha University Hospital. Sample: Consisted of all staff nurses (65). Tools: Data was collected by using two tools, workplace bullying questionnaire and nurses' job performance observation checklist. Results: The result showed that nearly three quarters (73.8%) of staff nurses had moderate level of bullying and more than three quarters (81.5%) of the staff nurses had satisfactory level of job performance Conclusion: There was no statistically significant correlation between nurses' workplace bullying and their performance. Recommendation: Nurses at all levels, including administrators and staff nurses, need to be educated to report bullying and nursing administrators need to develop policies to prevent bullying and anti-bullying reporting tools and mechanisms that allow nurses who exposed to workplace bullying to report incidents of bullying.