Abstract Background: The prevention of central venous line associated infection (CVLAI) represents a significant challenge in clinical setting, despite infection control advances. Nurses have a pivotal role in implementing preventive measures of CVLAI and patient care. However, various factors may influence their performance in this area. Study aim: Assess the factors affecting nurses' performance regarding prevention of central venous line associated infection. Design: A descriptive design was used to meet the aim of this study. Setting: Data was collected from surgical intensive care units at Zagazig university hospitals. Subjects: A convenience sample of all available nurses who worked in above mentioned setting. Tools: Three tools were used, Self-administered questionnaire to assess nurses’ demographic characteristics and knowledge; observation checklist to assess nurses’ practice; and factors assessment questionnaire to assess the factors that affecting nurses’ performance. Results: The current study revealed that 54.7% and 69.3% of the studied nurses had unsatisfactory overall knowledge and practice levels, respectively regarding prevention of CVLI. Also, 86.7% of nurses reported that their performance was affected by patient, nurse, and work-related factors. Conclusion: More than half of the studied nurses have an unsatisfactory overall knowledge level regarding prevention of central venous line associated infection as well as more than two third of nurses had unsatisfactory overall practice level. Also, majority of studied nurses’ performance was affected by patient, nurse, and work-related factors. Recommendation: The need for current evidence-based practice guidelines in the nursing education curriculum, and ongoing monitoring of staff nurses' practice while practicing central venous line insertion and care. Keywords: CVLAI prevention, Factors Affecting Nurses Performance