Recently health care organizations are moving quickly from the concept of a hierarchical organization to one that depends on teams. Ultimately, teams succeed when they are supported by the organization and when they are provided with a clear standard of high- performance expectation. Purpose of the study: Assess the perception of staff nurses about teamwork and its effect on their job performance. Design: A descriptive correlational research design was utilized for this study. Setting: Menoufia University Hospital at Shebin-ELkom. Sampling: Convenience sample of 292 nurses were included at this study. Instruments: Two instruments were used for data collection: Instrument one; Teamwork Perceptions Questionnaire. (TPQ), Instrument two; Observational checklist for measuring Job performance.Results: Nurses had a high perception level towards teamwork (87%). Also, 13% of studied nurses had a moderate perception level towards teamwork. In addition, about two thirds of studied nurses (65.80%) had a high performance level. Also, 34.20% of studied nurses had a moderate performance level. Conclusion: There was a positive highly statistical significant correlation between nurses' perception toward teamwork and their job performance. Recommendation: The hospital should provide effective and continuous training programs for nursing staff based on needs assessment to develop their knowledge and skills and consequently their teamwork and performance.